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Adsorption of adenine molecule on χ3 borophene nanosheets: A density functional theory study
Journal Pre-proof Adsorption of adenine molecule on 𝜒3 borophene nanosheets: A density functional theory study Shirin Sabokdast, Ashkan Horri, Yavar T. Azar, Maryam Momeni, Mohammad bagher Tavakoli
PII: DOI: Reference:
S1386-9477(19)31654-6 https://doi.org/10.1016/j.physe.2020.114026 PHYSE 114026
To appear in:
Physica E: Low-dimensional Systems and Nanostructures
Received date : 30 October 2019 Revised date : 9 January 2020 Accepted date : 12 February 2020 Please cite this article as: S. Sabokdast, A. Horri, Y.T. Azar et al., Adsorption of adenine molecule on 𝜒3 borophene nanosheets: A density functional theory study, Physica E: Low-dimensional Systems and Nanostructures (2020), doi: https://doi.org/10.1016/j.physe.2020.114026. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier B.V.
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Adsorption of Adenine Molecule on
χ3
Borophene Nanosheets: A Density
Functional Theory Study
Shirin Sabokdast,1 Ashkan Horri*,1 Yavar T. Azar,1 Maryam Momeni,2 and Mohammad bagher Tavakoli1
1) Department
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of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Irana) 2) Department of Electrical Engineering, Faculty of Engineering, Arak University, Arak, Iranb)
In this paper, we use density functional theory (DFT) method to study the adsorption properties of adenine molecule on the χ3 borophene nanosheets. The attributes of the adsorption at different molecule orientations and different selective positions are investigated. We found that interactions between adenine and selective points on borophene sheets result in chemical and physical adsorption that in some cases, high adsorption energy and charge transfer occurs well. Results indicate the strong potential of borophene in adsorption of the adenine molecule, so this two-dimensional material could be a suitable candidate for future DNA sequencing devices. I.
INTRODUCTION
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The design of fast, sensitive, and selective devices for detection of biological molecules has special importance in the diagnosis and clinical treatment. The major features of a biosensor are characterized in terms of its settling time, stability, sensitivity, and selectivity namely the “4s”[1]. The time taken by the biosensor to produce a stable signal change defines the settling time. According to transition state theory[1] settling time is inversely proportional to adsorption energy. Also, the adsorption energy of a molecule on a solid defines the stability of the molecule-solid complex. To evaluate the stability of molecule adsorption, the adsorption energies are calculated. More negative adsorption energy implies higher stability. Sensitivity corresponds to the relative change in sensor characteristics upon attachment of target molecules. Charge transfer and DOS affect the sensitivity of the sensor. More charge transfer and DOS variations result in higher sensitivity. Finally, Selectivity denotes the ability of receptors to bind with the desired target in the presence of various other bio-molecules. Recent advances in DNA sequencing technology have led to extensive developments in biomedical sciences and researches. With the emergence and development of nano-materials, the use of them in detection of biological molecules and their structures has been proposed and considered [1,2]. Nano-material based biosensors have been widely examined for the diagnosis of DNA nucleobases [2,3]. Twodimensional materials such as graphene [4], silicene[5], phosphorene [6], and molybdenum disulfide (MoS2 ) [7,8] are the most active nano-materials that due to their high surface to volume ratio and their unique electronic properties, have a high potential for use in nanoelectronics than their solid counterparts. Also recently, nanopore-based methods for DNA sequencing have been described in numerous papers [9-10]. In one study, by creating a nanopore in nanoribbon graphene and inserting four nucleobases of DNA into graphene nanopore, the conductance spectra, current, and density of states (DOS) were analyzed. The results indicate that unique conductance
a) Electronic
b) Electronic
mail: [email protected] mail: [email protected]
spectra and electronic characteristics have been developed for each nucleobase in the proposed device[10]. Also, DNA sequencing based on graphene-hBN heterostructure has been proposed [11]. In recent years, extensive studies have been conducted on the specific configuration of boron atoms called borophene due to its exciting electronic properties [12-13]. Remarkable high sensitivity to pollutant gases even at low concentrations has made it a good candidate for sensing applications. Some recent articles have investigated various structures of borophene about the adsorption of gas molecules such as SO2 , NO2 , NH3 , and NO [14-17]. The electronic sensitivity, reactivity, and adsorption energy of B36 borophene toward four nucleobases have been studied using density functional theory (DFT) calculations [18]. The purpose of this paper is to investigate the electronic behavior and adsorption properties of borophene in the framework of DFT driven by the development of DNA sequencing technology. The DNA consists of four nucleobases A (adenine), G (guanine), C (cytosine) and T (thymine). Previous study about three main phases of borophene sheets, i.e, striped, χ3 , and β12 , indicate that χ3 and β12 structures of borophene have better mechanical, thermodynamical and dynamical stability than the striped structure[19]. Therefore, in this paper, for the first time, we consider χ3 borophene structure to identify single nucleobase DNA(adenine). The organization of this paper is as follow: in Sec II, the physical structure and calculation method are described. In Sec. III, results are discussed. Finally, conclusions are presented in Sec. IV. II.
PHYSICAL STRUCTURE AND CALCULATION
METHOD
The calculations have been done using the SIESTA package in terms of DFT method [20]. DFT is a computational method that derives the electronic properties of the material based on a determination of the electron density of the molecule[20]. DFT method has been established as a valuable research tool because it can serve to validate the conclusions that have been reached from the analysis of the experiments. The major benefit of DFT method is the enhancement in computa-
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tional accuracy without the overhead of increasing the computing time. Thus, DFT is a suitable tool for describing a system with a large number of atoms [20]. The atomic core electrons were modeled with the norm-conserving TroullierMartin pseudopotentials[21]. The generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) function is used to approximate exchange-correlation. Also, we used DZP orbital bases in the calculations. All atoms were completely relaxed using conjugate gradient method with a force less than 0.03 eV/Å. The mesh cut-off is set to be 200Ry for all configurations. The integration over the Brillouin zone was performed using a scheme proposed by Monokhorst-Pack with a grid of 2 × 2 × 1 kpoints, and 6 × 6 × 1 for electronic structure calculations. The vacuum distance of 15 Å in the zdirection is considered to avoid interactions of monolayers to each other. The adsorption energy Ead is defined as follows: Ead = Etotal − (Eborophene + Eadenine )
(2)
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Where ρtotal , ρborophene , and ρadenine are the total charge density for (borophene+adenine) hybrid structure, isolated borophene, and isolated adenine, respectively. Also, charge transfer from/to the adenine molecule has been evaluated as an adsorption effect by Mulliken population analysis (difference before and after adsorption). More specifically, the charge transfer is calculated for each atom of the adenine molecule, namely the N, H, and C atoms before and after adsorption, and then the charge difference before adsorption and after adsorption is obtained. A positive Qt implies that the charge transfer from the borophene sheet to the adenine molecule has occurred and the negative value means vice versa.
III.
RESULT AND DISCUSSION
After the relaxation of rectangular unit cell of χ3 borophene, the optimized lattice constants of a = 8.47Å and b = 2.98Å, are obtained which are in good agreement with previous studies[22]. The adenine molecule also singly relaxed well with the parameters mentioned before. Fig.1 shows the structure of the adenine molecule and the structure of the χ3 planner borophene as well as the positions of the adenine molecule adsorption on the borophene sheet. We define the supercell sheet of borophene with 2 × a and 7 × b lattice constants at X and Y directions, respectively as shown in Fig.1(a). Also, the atomic position of adenine molecule is shown in Fig2.(b). To find the most favorable configuration of the adsorbents on the borophene layer, we place them on different initial sites with different orientations. The considered three adsorption positions for the adenine molecule are T, B, and
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T
H
N2 N3
C
N
H
(1)
Where, Etotal , Eborophene ,and Eadenine are energies of (borophene+Adenine) hybrid structure, isolated borophene, and isolated adenine, respectively. We also calculated the charge density difference defined by ∆ρ(r) = ρtotal (r) − ρborophene (r) − ρadenine (r)
B
FIG. 1. (a) χ3 borophene structure. Adenine molecule adsorption sites are marked with red points. (b) Adenine molecule structure.
H, which represent top, bridge, and hollow positions, respectively. Also, three different orientations for adenine molecule, i.e, horizontal, vertical and oblique 45◦ directions, are considered. Given that the molecule of adenine has three free Nitrogen atoms which are more capable of adsorption than other adenine atoms, we rotate the adenine molecule on the surface of borophene so that each of the atoms N1, N2, and N3 can locate in T, B, and H adsorption positions of adenine molecules. Therefore we have 27 total configurations. Overall, appropriate sensing should have proper sensitivity and selectivity. If the borophene sheet is effective as an application sensor for detecting nucleobases (DNA), enough charge transfer with proper adsorption energy is necessary for electrical conductivity in that sheet. The (χ3 borophene+adenine) hybrid structure is relaxed by placing the adenine molecule at one of the probable positions of adsorption (27 positions). After relaxation, we calculated the charge transfer parameters, the adsorption energy and the shortest distance between the molecule and the surface of borophene. These parameters are calculated by Mulliken population analysis and charge density difference. These values are summarized at Table I. The states bolded in the table I, have the lower adsorption energy and higher charge transfer in comparison with other states. These eight atomic configurations are shown in Fig.2. The charge density difference of these eight stable structures is shown in Fig.3. As shown in the figure, the areas with increase in charge density are shown by yellow color and the areas with decrease in charge density are shown by blue one. To find more about the electronic properties of the adsorbed adenine molecule on the borophene sheet, the DOS for the most stable states adsorption, are calculated. The DOS with regard to the adsorption of adenine molecule (adsorbent and adsorbate system) are shown in Fig. 4. A small gaussian broadening is considered in our calculations to achieve
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TABLE I. The charge transfer, the adsorption energy and distance values in different orientations and sites.
(g)
Adenine Atom
Site
Ead (eV ) Distance(Å) Qt (e)
Horizontal Horizontal Horizontal
N1 N2 N3
B B B
-1.409 -1.94 -1.685
3.168 1.6 1.624
-0.25 -0.75 -0.7
Horizontal Horizontal Horizontal
N1 N2 N3
H H H
-1.94 -1.429 -1.429
1.6 3.36 3.36
-0.75 -0.236 -0.236
Horizontal Horizontal Horizontal
N1 N2 N3
T T T
-1.685 -1.685 -1.409
1.624 1.624 3.168
-0.7 -0.7 -0.25
Vertical Vertical Vertical
N1 N2 N3
B B B
-1.994 -2.306 -2.088
1.603 1.591 1.6
-0.555 -0.632 -0.553
Vertical Vertical Vertical
N1 N2 N3
H H H
-0.9538 -0.9188 -0.8426
3.12 3.15 3.162
-0.035 -0.09 -0.073
Vertical Vertical Vertical
N1 N2 N3
T T T
-1.961 -2.294 -2.077
1.602 1.602 1.607
-0.590 -0.593 -0.566
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
B B B
-1.991 -1.4 -1.462
1.593 3.066 3.056
-0.611 -0.207 -0.218
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
H H H
-1.439 -1.48 -1.451
3.112 3.22 3.09
-0.224 -0.236 -0.228
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
T T T
-1.746 -2.090 -1.909
1.615 1.593 1.602
-0.503 -0.632 -0.632
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Orientation
FIG. 2. Atomic structure of relaxed system when adenine molecule is in (a) horizontal orientation and N1 atom is located at T site, (b) horizontal orientation and N2 atom is located at B site, (c) vertical orientation and N2 atom is located at T site, (d) vertical orientation and N1 atom is located at H site, (e) vertical orientation and N2 atom is located at B site, (f) oblique orientation and N2 atom is located at T site, (g) oblique orientation and N2 atom is located at H site, (h) oblique orientation and N1 atom is located at B site.
higher accuracy which leads to noisy behavior of DOS plots. Increasing the broadening value leads to the smoothening of DOS curves. Depending on adenine position and orientation, adsorption on borophene sheets occurs chemically or physically. Physical adsorption is the result of a relatively weak solid-molecule interaction. Physical attractions are nonspecific with relatively weak Van der Waal’s forces and adsorption energy. Physically adsorbed molecules may diffuse along the surface of the adsorbent and typically are not bound to a specific location on the surface. Being only weakly bound, physical adsorption is easily reversed. A chemical bond involves the sharing of electrons between the adsorbate and the adsorbent and may be regarded as the formation of a surface compound. Due to the bond strength, chemical adsorption is difficult to reverse. Physical adsorption takes place on all surfaces provided that temperature and pressure conditions are favorable. Chemical adsorption, however, is highly selective and occurs only between certain adsorptive[23]. In the state of (a), the
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(b)
(b)
(d)
(e)
(f)
(g)
(h)
FIG. 3. Charge density difference maps for (a-h) structures.
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adenine molecule is positioned horizontally on the borophene sheet so that N1 atom is located in position of T. In this state with the adsorption energy of -1.685(eV) between the N1 atom and the borophene atom (B-N), the chemical bond is formed with the bond length of 1.624Å as shown in Fig.2(a). In this case, %7 change in DOS is observed. In the state of (b), we positioned the adenine molecule horizontally so that the N2 atom is at point of B. In this state, with the adsorption energy of -1.94(eV) between the N2 atom and the borophene atom, a chemical bond is formed with bond length of 1.60 Å(Fig.2(b)). In this case, %7.47 change in DOS is observed. In horizontal state, when the N1 atom is located in H point, the results is same as previous case (N2 at B point). In the state of (c), we put the molecule of adenine so that the N2 atom is vertically at point of T(Fig.2(c)). In this case, chemical bond is formed between the N2 and boron atoms with a bond length of 1.602 Å and the adsorption energy of -2.294(eV). In this case, %5.63 change in DOS is observed. N1 and N3 atoms were also vertically positioned in this place. Their adsorption energies were -1.96eV and -2.078eV, respectively, and chemical adsorption occurs in both states. In the state of (d), we positioned the adenine molecule so that the N1 atom is placed vertically at the H point. The molecule is physically adsorbed in this state and is positioned 3.12 Å away from the borophene sheet Fig.2(d). Also, for the N2 and N3 atoms, this position was investigated. In these two states the adsorption energy was more positive than N1 state and the molecule is far away from the borophene sheet. In this case, %7.24 change in DOS is observed. In the state of (e), we positioned the adenine molecule so that the N2 atom is placed vertically at point B. This state has the lowest adsorption energy between the directions and the adsorption positions. The molecule has less distance form boron atoms than the other directions and possible adsorption positions Fig.2(e). In this case, %5.86 change in DOS is observed. Also, the 45◦ rotation of adenine molecule on the borophene sheet is consid-
DOS (States/eV)
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(a)
(e)
E-EF(eV)
E-EF(eV)
FIG. 4. Electronic density of states (DOS) for (a-h) structures. (E − EF ) is energy difference from Fermi level energy. In each case, the Fermi level energy is set to zero, indicated by the dotted line.
ered. In the state of (f), the molecule of adenine is at a 45◦ angle respect to the borophene sheet so that the N2 atom is in the T position. A chemical bond is formed between N2 and B atom with a bond length of 1.593Å and the adsorption energy of -2.09(eV). In this case, %6.09 change in DOS is observed. In the state of (g), the N2 atom is in h position and the adenine molecule was also placed at an angle of 45◦ in H position. The results show that the adenine molecule is physically adsorbed on the borophene sheet Fig.2(g). In this case, %7.35 change in DOS is observed. In the state of (h), the N1 atom is in B position and with the bond length of 1.592Å is chemically adsorbed at an angle of 45◦ .In this case, %6.43 change in DOS is observed. States which have high adsorption energy with a short atomic distance and large charge transfer, indicate that a chemical bond (N-B) is formed for that structure. Horizontal state defined at three positions have high chemical adsorption energy and charge transfer. In vertical directions especially at (e) state, the highest adsorption energy was obtained rel-
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IV.
CONCLUSION
1 K.
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In this paper, we investigate the adsorption of adenine molecules on a borophene sheet using a density functional theory. The adsorption geometry and optimum positions of the adenine molecule adsorption on the borophene sheet were determined in different directions. It was found that in some positions and directions of the borophene sheet, where the adsorption occurred physically, the energy of the adsorption and charge transfer was higher than the other cases where the chemical adsorption occurred. These results indicate that election of proper position and direction of the adenine molecule on the surface of borophene affects the selectivity and sensitivity of borophene. So this data helps adenine to be in the best position and direction that borophene is sensitive to its detection. The high adsorption energies and high charge transfer of borophene have made this two-dimensional material an appropriate candidate for application in detection sensors of nucleotides. The only cases that may make it difficult to use this material as a DNA detection sensor is the deformation of borophene sheets during the adsorption process of the adenine molecule and on the other hand with regard to high adsorption energy, at the positions and directions that the adenine on the borophene sheet has been chemically adsorbed, it prohibits reusability the use of this material as a sensor detection nucleobases.
V.
graphene: single-molecular adsorption and overlayer binding,’, Journal of Physics: Condensed Matter, 2011, 23, pp.135001. 2 H. S. Kim and Y.-H. Kim,: ‘Recent progress in atomistic simulation of electrical current DNA sequencing,’,Biosensors and Bioelectronics, 2015, 69, pp.186-198. 3 S. J. Heerema and C. Dekker,: ‘Graphene nanodevices for DNA sequencing,’, Nature nanotechnology., 2016, 11, pp.127. 4 J. Beheshtian, A. A. Peyghan, and M. Noei,: ‘Sensing behavior of Al and Si doped BC3 graphenes to formaldehyde,’, Sensors and Actuators B,, 2013,181, pp. 829-834. 5 H. Dai, P. Xiao, and Q. Lou,: ‘Application of SnO2/MWCNTs nanocomposite for SF6 decomposition gas sensor,’, physica status solidi (a), 2011,208, pp. 1714-1717. 6 M. Batmunkh, M. Bat-Erdene, and J. G. Shapter,:‘Phosphorene and Phosphorene-Based Materials–Prospects for Future Applications,’, Advanced Materials, 2016, 28,pp. 8586-8617. 7 A. Shokri and N. Salami,: ‘Gas sensor based on MoS2 monolayer,’, Sensors and Actuators B,, 2016,236, pp. 378-385. 8 S.M. Tabatabaei, M. Pourfath, and M. Fathipour,: ‘Adsorption characteristics of epigenetically modified DNA nucleobases on single-layer MoS2: A first-principles study,"’, Journal of Applied Physics,., 2018, 124, pp.134501. 9 G. Sigalov, J. Comer, G. Timp, and A. Aksimentiev,: ‘Detection of DNA sequences using an alternating electric field in a nanopore capacitor,’, Nano letters,., 2008, 8, pp.56-63. 10 T. Nelson, B. Zhang, and O. V. Prezhdo,: ‘Detection of nucleic acids with graphene nanopores: ab initio characterization of a novel sequencing device,’, Nano letters,., 2010, 10, pp.3237-3242. 11 V. Shukla, N. K. Jena, A. Grigoriev, and R. Ahuja,: ‘Prospects of Graphene–hBN Heterostructure Nanogap for DNA Sequencing,’, ACS applied materials and interfaces,., 2017, 9, pp.39945-39952. 12 A. J. Mannix et al.,: ‘Synthesis of borophenes: Anisotropic, twodimensional boron polymorphs,’, Science, 2015,350, pp. 1513-1516. 13 Ashkan Horri, Rahim Faez.,: ‘Tight-binding model for the electronic properties of buckled triangular borophene,’, Micro and Nano Letters,., 2019, 14, pp. 992–994. 14 H. Cui, X. Zhang, and D. Chen,: ‘Borophene: a promising adsorbent material with strong ability and capacity for SO 2 adsorption,’, Applied Physics A,., 2018, 124, pp. 636. 15 C.-S. Huang, A. Murat, V. Babar, E. Montes, and U. Schwingenschlogl,: ‘Adsorption of the Gas Molecules NH3, NO, NO2, and CO on Borophene,’, The Journal of Physical Chemistry C., 2018, 122, pp. 14665-14670. 16 T. Liu et al.,: ‘A first-principles study of gas molecule adsorption on borophene,’, Aip Advances,., 2017, 7, pp.125007. 17 V. Shukla, J. Warna, N. K. Jena, A. Grigoriev, and R. Ahuja,: ‘Toward the realization of 2D borophene based gas sensor,’, The Journal of Physical Chemistry C,., 2017, 121, pp.26869-26876. 18 A. Rastgou, H. Soleymanabadi, and A. Bodaghi,: ‘DNA sequencing by borophene nanosheet via an electronic response: a theoretical study,’, Microelectronic Engineering,., 2017, 169, pp.9-15. 19 B. Peng et al.,: ‘Stability and strength of atomically thin borophene from first principles calculations,’, Materials Research Letters., 2017, 5, pp.399407. 20 P. Ordejón, E. Artacho, and J. M. Soler,: ‘Self-consistent order-N densityfunctional calculations for very large systems,’, Physical Review B,., 1996, 53, pp.R10441. 21 N. Troullier and J. L. Martins,: ‘Efficient pseudopotentials for plane-wave calculations,’, Physical review B,, 1991, 43, pp.1993 22 M. Boroun, S. Abdolhosseini, and M. Pourfath,: ‘Separated and intermixed phases of borophene as anode material for lithium-Ion batteries,’, Journal of Physics D: Applied Physics,, 2019, 52, pp.245501 23 E. Zaremba and W. Kohn,: ‘Theory of helium adsorption on simple and noble-metal surfaces,’, Physical Review B,, 1977, 15, pp.1769
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ative to the horizontal and 45◦ rotated directions. From the Table, it can be found that, in most cases, the charge transfer in horizontal states is higher than vertical or oblique configuration. When the adenine molecule is in the vertical or oblique orientation, most charge transfer occurs at B and T sites. Also, it can be found that in each orientation, the lowest charge transfer occurs at H site. A comparison between horizontal and vertical orientation indicates that vertical orientation has lower adsorption energy, hence, it is more stable than the horizontal direction. But horizontal direction has higher charge transfer. According to adsorption energies provided in Table I, oblique(45◦ ) orientation, is less stable than vertical orientation, But its charge transfer in some sites increases and in other site decreases. These eight configurations reported in the table I have the lowest adsorption energy in comparison with all 27 configurations. The adsorption energy of adenine on MoS2 and B36 are -0.77eV and -0.84eV, respectively[8,18]. The quantities of adsorption energy of the χ3 phase of borophene compared to these materials indicate the high power of this substance for adsorption of an adenine molecule.
REFERENCES
Berland, S. D. Chakarova-Käck, V. R. Cooper, D. C. Langreth, and E. Schröder: ‘A van der Waals density functional study of adenine on
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HIGHLIGHTS
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In this paper, we investigate the adsorption of adenine molecules on a borophene sheet using a density functional theory. The adsorption geometry and optimum positions of the adenine molecule adsorption on the borophene sheet were determined in different directions. It was found that in some positions and directions of the borophene sheet, where the adsorption occurred physically, the energy of the adsorption and charge transfer was higher than the other cases where the chemical adsorption occurred. Results indicate the strong potential of borophene in adsorption of the adenine molecule, so this two-dimensional material could be a suitable candidate for future DNA sequencing devices.
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Conflict of Interest Form Systems
and
Nanostructures:
Manuscript
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Physica E: Low-dimensional #PHYSE_2019_1582
Title: “Adsorption of Adenine Molecule on χ3 Borophene Nanosheets: A Density Functional Theory Study”
√ All authors declare no conflict of interest and have participated in (a) conception and design, or analysis and interpretation of the data; (b) drafting the article or revising it critically for important intellectual content; and (c) approval of the final version. √ This manuscript has not been submitted to, nor is under review at, another journal or other publishing venue.
√ The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript √ The following authors have affiliations with organizations with direct or indirect financial interest in the subject matter discussed in the manuscript: Author’s name
Affiliation
Iran
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Shirin Sabokdast Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Ashkan Horri Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Yavar T. Azar Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Maryam Momeni Department of Electrical Engineering, Faculty of Engineering, Arak University, Arak, Mohammad bagher tavakoli
Department of Electrical Engineering, Arak Branch, Islamic Azad University,
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Arak, Iran
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According to International Committee of Medical Journal Editors (ICMJE): “An author is considered to be someone who has made substantive intellectual contributions to a published study. An author must take responsibility for at least one component of the work, should be able to identify who is responsible for each other component, and should ideally be confident in their co-authors’ ability and integrity. “ (available at: http://www.icmje.org/ethical_1author.html)
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Ashkan Horri- Yavar T Azar Ashkan Horri Ashkan Horri Ashkan Horri Ashkan Horri
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1
PII: DOI: Reference:
S1386-9477(19)31654-6 https://doi.org/10.1016/j.physe.2020.114026 PHYSE 114026
To appear in:
Physica E: Low-dimensional Systems and Nanostructures
Received date : 30 October 2019 Revised date : 9 January 2020 Accepted date : 12 February 2020 Please cite this article as: S. Sabokdast, A. Horri, Y.T. Azar et al., Adsorption of adenine molecule on 𝜒3 borophene nanosheets: A density functional theory study, Physica E: Low-dimensional Systems and Nanostructures (2020), doi: https://doi.org/10.1016/j.physe.2020.114026. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier B.V.
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Adsorption of Adenine Molecule on
χ3
Borophene Nanosheets: A Density
Functional Theory Study
Shirin Sabokdast,1 Ashkan Horri*,1 Yavar T. Azar,1 Maryam Momeni,2 and Mohammad bagher Tavakoli1
1) Department
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of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Irana) 2) Department of Electrical Engineering, Faculty of Engineering, Arak University, Arak, Iranb)
In this paper, we use density functional theory (DFT) method to study the adsorption properties of adenine molecule on the χ3 borophene nanosheets. The attributes of the adsorption at different molecule orientations and different selective positions are investigated. We found that interactions between adenine and selective points on borophene sheets result in chemical and physical adsorption that in some cases, high adsorption energy and charge transfer occurs well. Results indicate the strong potential of borophene in adsorption of the adenine molecule, so this two-dimensional material could be a suitable candidate for future DNA sequencing devices. I.
INTRODUCTION
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The design of fast, sensitive, and selective devices for detection of biological molecules has special importance in the diagnosis and clinical treatment. The major features of a biosensor are characterized in terms of its settling time, stability, sensitivity, and selectivity namely the “4s”[1]. The time taken by the biosensor to produce a stable signal change defines the settling time. According to transition state theory[1] settling time is inversely proportional to adsorption energy. Also, the adsorption energy of a molecule on a solid defines the stability of the molecule-solid complex. To evaluate the stability of molecule adsorption, the adsorption energies are calculated. More negative adsorption energy implies higher stability. Sensitivity corresponds to the relative change in sensor characteristics upon attachment of target molecules. Charge transfer and DOS affect the sensitivity of the sensor. More charge transfer and DOS variations result in higher sensitivity. Finally, Selectivity denotes the ability of receptors to bind with the desired target in the presence of various other bio-molecules. Recent advances in DNA sequencing technology have led to extensive developments in biomedical sciences and researches. With the emergence and development of nano-materials, the use of them in detection of biological molecules and their structures has been proposed and considered [1,2]. Nano-material based biosensors have been widely examined for the diagnosis of DNA nucleobases [2,3]. Twodimensional materials such as graphene [4], silicene[5], phosphorene [6], and molybdenum disulfide (MoS2 ) [7,8] are the most active nano-materials that due to their high surface to volume ratio and their unique electronic properties, have a high potential for use in nanoelectronics than their solid counterparts. Also recently, nanopore-based methods for DNA sequencing have been described in numerous papers [9-10]. In one study, by creating a nanopore in nanoribbon graphene and inserting four nucleobases of DNA into graphene nanopore, the conductance spectra, current, and density of states (DOS) were analyzed. The results indicate that unique conductance
a) Electronic
b) Electronic
mail: [email protected] mail: [email protected]
spectra and electronic characteristics have been developed for each nucleobase in the proposed device[10]. Also, DNA sequencing based on graphene-hBN heterostructure has been proposed [11]. In recent years, extensive studies have been conducted on the specific configuration of boron atoms called borophene due to its exciting electronic properties [12-13]. Remarkable high sensitivity to pollutant gases even at low concentrations has made it a good candidate for sensing applications. Some recent articles have investigated various structures of borophene about the adsorption of gas molecules such as SO2 , NO2 , NH3 , and NO [14-17]. The electronic sensitivity, reactivity, and adsorption energy of B36 borophene toward four nucleobases have been studied using density functional theory (DFT) calculations [18]. The purpose of this paper is to investigate the electronic behavior and adsorption properties of borophene in the framework of DFT driven by the development of DNA sequencing technology. The DNA consists of four nucleobases A (adenine), G (guanine), C (cytosine) and T (thymine). Previous study about three main phases of borophene sheets, i.e, striped, χ3 , and β12 , indicate that χ3 and β12 structures of borophene have better mechanical, thermodynamical and dynamical stability than the striped structure[19]. Therefore, in this paper, for the first time, we consider χ3 borophene structure to identify single nucleobase DNA(adenine). The organization of this paper is as follow: in Sec II, the physical structure and calculation method are described. In Sec. III, results are discussed. Finally, conclusions are presented in Sec. IV. II.
PHYSICAL STRUCTURE AND CALCULATION
METHOD
The calculations have been done using the SIESTA package in terms of DFT method [20]. DFT is a computational method that derives the electronic properties of the material based on a determination of the electron density of the molecule[20]. DFT method has been established as a valuable research tool because it can serve to validate the conclusions that have been reached from the analysis of the experiments. The major benefit of DFT method is the enhancement in computa-
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tional accuracy without the overhead of increasing the computing time. Thus, DFT is a suitable tool for describing a system with a large number of atoms [20]. The atomic core electrons were modeled with the norm-conserving TroullierMartin pseudopotentials[21]. The generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) function is used to approximate exchange-correlation. Also, we used DZP orbital bases in the calculations. All atoms were completely relaxed using conjugate gradient method with a force less than 0.03 eV/Å. The mesh cut-off is set to be 200Ry for all configurations. The integration over the Brillouin zone was performed using a scheme proposed by Monokhorst-Pack with a grid of 2 × 2 × 1 kpoints, and 6 × 6 × 1 for electronic structure calculations. The vacuum distance of 15 Å in the zdirection is considered to avoid interactions of monolayers to each other. The adsorption energy Ead is defined as follows: Ead = Etotal − (Eborophene + Eadenine )
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Where ρtotal , ρborophene , and ρadenine are the total charge density for (borophene+adenine) hybrid structure, isolated borophene, and isolated adenine, respectively. Also, charge transfer from/to the adenine molecule has been evaluated as an adsorption effect by Mulliken population analysis (difference before and after adsorption). More specifically, the charge transfer is calculated for each atom of the adenine molecule, namely the N, H, and C atoms before and after adsorption, and then the charge difference before adsorption and after adsorption is obtained. A positive Qt implies that the charge transfer from the borophene sheet to the adenine molecule has occurred and the negative value means vice versa.
III.
RESULT AND DISCUSSION
After the relaxation of rectangular unit cell of χ3 borophene, the optimized lattice constants of a = 8.47Å and b = 2.98Å, are obtained which are in good agreement with previous studies[22]. The adenine molecule also singly relaxed well with the parameters mentioned before. Fig.1 shows the structure of the adenine molecule and the structure of the χ3 planner borophene as well as the positions of the adenine molecule adsorption on the borophene sheet. We define the supercell sheet of borophene with 2 × a and 7 × b lattice constants at X and Y directions, respectively as shown in Fig.1(a). Also, the atomic position of adenine molecule is shown in Fig2.(b). To find the most favorable configuration of the adsorbents on the borophene layer, we place them on different initial sites with different orientations. The considered three adsorption positions for the adenine molecule are T, B, and
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N2 N3
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H
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Where, Etotal , Eborophene ,and Eadenine are energies of (borophene+Adenine) hybrid structure, isolated borophene, and isolated adenine, respectively. We also calculated the charge density difference defined by ∆ρ(r) = ρtotal (r) − ρborophene (r) − ρadenine (r)
B
FIG. 1. (a) χ3 borophene structure. Adenine molecule adsorption sites are marked with red points. (b) Adenine molecule structure.
H, which represent top, bridge, and hollow positions, respectively. Also, three different orientations for adenine molecule, i.e, horizontal, vertical and oblique 45◦ directions, are considered. Given that the molecule of adenine has three free Nitrogen atoms which are more capable of adsorption than other adenine atoms, we rotate the adenine molecule on the surface of borophene so that each of the atoms N1, N2, and N3 can locate in T, B, and H adsorption positions of adenine molecules. Therefore we have 27 total configurations. Overall, appropriate sensing should have proper sensitivity and selectivity. If the borophene sheet is effective as an application sensor for detecting nucleobases (DNA), enough charge transfer with proper adsorption energy is necessary for electrical conductivity in that sheet. The (χ3 borophene+adenine) hybrid structure is relaxed by placing the adenine molecule at one of the probable positions of adsorption (27 positions). After relaxation, we calculated the charge transfer parameters, the adsorption energy and the shortest distance between the molecule and the surface of borophene. These parameters are calculated by Mulliken population analysis and charge density difference. These values are summarized at Table I. The states bolded in the table I, have the lower adsorption energy and higher charge transfer in comparison with other states. These eight atomic configurations are shown in Fig.2. The charge density difference of these eight stable structures is shown in Fig.3. As shown in the figure, the areas with increase in charge density are shown by yellow color and the areas with decrease in charge density are shown by blue one. To find more about the electronic properties of the adsorbed adenine molecule on the borophene sheet, the DOS for the most stable states adsorption, are calculated. The DOS with regard to the adsorption of adenine molecule (adsorbent and adsorbate system) are shown in Fig. 4. A small gaussian broadening is considered in our calculations to achieve
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TABLE I. The charge transfer, the adsorption energy and distance values in different orientations and sites.
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Adenine Atom
Site
Ead (eV ) Distance(Å) Qt (e)
Horizontal Horizontal Horizontal
N1 N2 N3
B B B
-1.409 -1.94 -1.685
3.168 1.6 1.624
-0.25 -0.75 -0.7
Horizontal Horizontal Horizontal
N1 N2 N3
H H H
-1.94 -1.429 -1.429
1.6 3.36 3.36
-0.75 -0.236 -0.236
Horizontal Horizontal Horizontal
N1 N2 N3
T T T
-1.685 -1.685 -1.409
1.624 1.624 3.168
-0.7 -0.7 -0.25
Vertical Vertical Vertical
N1 N2 N3
B B B
-1.994 -2.306 -2.088
1.603 1.591 1.6
-0.555 -0.632 -0.553
Vertical Vertical Vertical
N1 N2 N3
H H H
-0.9538 -0.9188 -0.8426
3.12 3.15 3.162
-0.035 -0.09 -0.073
Vertical Vertical Vertical
N1 N2 N3
T T T
-1.961 -2.294 -2.077
1.602 1.602 1.607
-0.590 -0.593 -0.566
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
B B B
-1.991 -1.4 -1.462
1.593 3.066 3.056
-0.611 -0.207 -0.218
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
H H H
-1.439 -1.48 -1.451
3.112 3.22 3.09
-0.224 -0.236 -0.228
Oblique(45◦ ) Oblique(45◦ ) Oblique(45◦ )
N1 N2 N3
T T T
-1.746 -2.090 -1.909
1.615 1.593 1.602
-0.503 -0.632 -0.632
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Orientation
FIG. 2. Atomic structure of relaxed system when adenine molecule is in (a) horizontal orientation and N1 atom is located at T site, (b) horizontal orientation and N2 atom is located at B site, (c) vertical orientation and N2 atom is located at T site, (d) vertical orientation and N1 atom is located at H site, (e) vertical orientation and N2 atom is located at B site, (f) oblique orientation and N2 atom is located at T site, (g) oblique orientation and N2 atom is located at H site, (h) oblique orientation and N1 atom is located at B site.
higher accuracy which leads to noisy behavior of DOS plots. Increasing the broadening value leads to the smoothening of DOS curves. Depending on adenine position and orientation, adsorption on borophene sheets occurs chemically or physically. Physical adsorption is the result of a relatively weak solid-molecule interaction. Physical attractions are nonspecific with relatively weak Van der Waal’s forces and adsorption energy. Physically adsorbed molecules may diffuse along the surface of the adsorbent and typically are not bound to a specific location on the surface. Being only weakly bound, physical adsorption is easily reversed. A chemical bond involves the sharing of electrons between the adsorbate and the adsorbent and may be regarded as the formation of a surface compound. Due to the bond strength, chemical adsorption is difficult to reverse. Physical adsorption takes place on all surfaces provided that temperature and pressure conditions are favorable. Chemical adsorption, however, is highly selective and occurs only between certain adsorptive[23]. In the state of (a), the
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FIG. 3. Charge density difference maps for (a-h) structures.
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adenine molecule is positioned horizontally on the borophene sheet so that N1 atom is located in position of T. In this state with the adsorption energy of -1.685(eV) between the N1 atom and the borophene atom (B-N), the chemical bond is formed with the bond length of 1.624Å as shown in Fig.2(a). In this case, %7 change in DOS is observed. In the state of (b), we positioned the adenine molecule horizontally so that the N2 atom is at point of B. In this state, with the adsorption energy of -1.94(eV) between the N2 atom and the borophene atom, a chemical bond is formed with bond length of 1.60 Å(Fig.2(b)). In this case, %7.47 change in DOS is observed. In horizontal state, when the N1 atom is located in H point, the results is same as previous case (N2 at B point). In the state of (c), we put the molecule of adenine so that the N2 atom is vertically at point of T(Fig.2(c)). In this case, chemical bond is formed between the N2 and boron atoms with a bond length of 1.602 Å and the adsorption energy of -2.294(eV). In this case, %5.63 change in DOS is observed. N1 and N3 atoms were also vertically positioned in this place. Their adsorption energies were -1.96eV and -2.078eV, respectively, and chemical adsorption occurs in both states. In the state of (d), we positioned the adenine molecule so that the N1 atom is placed vertically at the H point. The molecule is physically adsorbed in this state and is positioned 3.12 Å away from the borophene sheet Fig.2(d). Also, for the N2 and N3 atoms, this position was investigated. In these two states the adsorption energy was more positive than N1 state and the molecule is far away from the borophene sheet. In this case, %7.24 change in DOS is observed. In the state of (e), we positioned the adenine molecule so that the N2 atom is placed vertically at point B. This state has the lowest adsorption energy between the directions and the adsorption positions. The molecule has less distance form boron atoms than the other directions and possible adsorption positions Fig.2(e). In this case, %5.86 change in DOS is observed. Also, the 45◦ rotation of adenine molecule on the borophene sheet is consid-
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FIG. 4. Electronic density of states (DOS) for (a-h) structures. (E − EF ) is energy difference from Fermi level energy. In each case, the Fermi level energy is set to zero, indicated by the dotted line.
ered. In the state of (f), the molecule of adenine is at a 45◦ angle respect to the borophene sheet so that the N2 atom is in the T position. A chemical bond is formed between N2 and B atom with a bond length of 1.593Å and the adsorption energy of -2.09(eV). In this case, %6.09 change in DOS is observed. In the state of (g), the N2 atom is in h position and the adenine molecule was also placed at an angle of 45◦ in H position. The results show that the adenine molecule is physically adsorbed on the borophene sheet Fig.2(g). In this case, %7.35 change in DOS is observed. In the state of (h), the N1 atom is in B position and with the bond length of 1.592Å is chemically adsorbed at an angle of 45◦ .In this case, %6.43 change in DOS is observed. States which have high adsorption energy with a short atomic distance and large charge transfer, indicate that a chemical bond (N-B) is formed for that structure. Horizontal state defined at three positions have high chemical adsorption energy and charge transfer. In vertical directions especially at (e) state, the highest adsorption energy was obtained rel-
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IV.
CONCLUSION
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In this paper, we investigate the adsorption of adenine molecules on a borophene sheet using a density functional theory. The adsorption geometry and optimum positions of the adenine molecule adsorption on the borophene sheet were determined in different directions. It was found that in some positions and directions of the borophene sheet, where the adsorption occurred physically, the energy of the adsorption and charge transfer was higher than the other cases where the chemical adsorption occurred. These results indicate that election of proper position and direction of the adenine molecule on the surface of borophene affects the selectivity and sensitivity of borophene. So this data helps adenine to be in the best position and direction that borophene is sensitive to its detection. The high adsorption energies and high charge transfer of borophene have made this two-dimensional material an appropriate candidate for application in detection sensors of nucleotides. The only cases that may make it difficult to use this material as a DNA detection sensor is the deformation of borophene sheets during the adsorption process of the adenine molecule and on the other hand with regard to high adsorption energy, at the positions and directions that the adenine on the borophene sheet has been chemically adsorbed, it prohibits reusability the use of this material as a sensor detection nucleobases.
V.
graphene: single-molecular adsorption and overlayer binding,’, Journal of Physics: Condensed Matter, 2011, 23, pp.135001. 2 H. S. Kim and Y.-H. Kim,: ‘Recent progress in atomistic simulation of electrical current DNA sequencing,’,Biosensors and Bioelectronics, 2015, 69, pp.186-198. 3 S. J. Heerema and C. Dekker,: ‘Graphene nanodevices for DNA sequencing,’, Nature nanotechnology., 2016, 11, pp.127. 4 J. Beheshtian, A. A. Peyghan, and M. Noei,: ‘Sensing behavior of Al and Si doped BC3 graphenes to formaldehyde,’, Sensors and Actuators B,, 2013,181, pp. 829-834. 5 H. Dai, P. Xiao, and Q. Lou,: ‘Application of SnO2/MWCNTs nanocomposite for SF6 decomposition gas sensor,’, physica status solidi (a), 2011,208, pp. 1714-1717. 6 M. Batmunkh, M. Bat-Erdene, and J. G. Shapter,:‘Phosphorene and Phosphorene-Based Materials–Prospects for Future Applications,’, Advanced Materials, 2016, 28,pp. 8586-8617. 7 A. Shokri and N. Salami,: ‘Gas sensor based on MoS2 monolayer,’, Sensors and Actuators B,, 2016,236, pp. 378-385. 8 S.M. Tabatabaei, M. Pourfath, and M. Fathipour,: ‘Adsorption characteristics of epigenetically modified DNA nucleobases on single-layer MoS2: A first-principles study,"’, Journal of Applied Physics,., 2018, 124, pp.134501. 9 G. Sigalov, J. Comer, G. Timp, and A. Aksimentiev,: ‘Detection of DNA sequences using an alternating electric field in a nanopore capacitor,’, Nano letters,., 2008, 8, pp.56-63. 10 T. Nelson, B. Zhang, and O. V. Prezhdo,: ‘Detection of nucleic acids with graphene nanopores: ab initio characterization of a novel sequencing device,’, Nano letters,., 2010, 10, pp.3237-3242. 11 V. Shukla, N. K. Jena, A. Grigoriev, and R. Ahuja,: ‘Prospects of Graphene–hBN Heterostructure Nanogap for DNA Sequencing,’, ACS applied materials and interfaces,., 2017, 9, pp.39945-39952. 12 A. J. Mannix et al.,: ‘Synthesis of borophenes: Anisotropic, twodimensional boron polymorphs,’, Science, 2015,350, pp. 1513-1516. 13 Ashkan Horri, Rahim Faez.,: ‘Tight-binding model for the electronic properties of buckled triangular borophene,’, Micro and Nano Letters,., 2019, 14, pp. 992–994. 14 H. Cui, X. Zhang, and D. Chen,: ‘Borophene: a promising adsorbent material with strong ability and capacity for SO 2 adsorption,’, Applied Physics A,., 2018, 124, pp. 636. 15 C.-S. Huang, A. Murat, V. Babar, E. Montes, and U. Schwingenschlogl,: ‘Adsorption of the Gas Molecules NH3, NO, NO2, and CO on Borophene,’, The Journal of Physical Chemistry C., 2018, 122, pp. 14665-14670. 16 T. Liu et al.,: ‘A first-principles study of gas molecule adsorption on borophene,’, Aip Advances,., 2017, 7, pp.125007. 17 V. Shukla, J. Warna, N. K. Jena, A. Grigoriev, and R. Ahuja,: ‘Toward the realization of 2D borophene based gas sensor,’, The Journal of Physical Chemistry C,., 2017, 121, pp.26869-26876. 18 A. Rastgou, H. Soleymanabadi, and A. Bodaghi,: ‘DNA sequencing by borophene nanosheet via an electronic response: a theoretical study,’, Microelectronic Engineering,., 2017, 169, pp.9-15. 19 B. Peng et al.,: ‘Stability and strength of atomically thin borophene from first principles calculations,’, Materials Research Letters., 2017, 5, pp.399407. 20 P. Ordejón, E. Artacho, and J. M. Soler,: ‘Self-consistent order-N densityfunctional calculations for very large systems,’, Physical Review B,., 1996, 53, pp.R10441. 21 N. Troullier and J. L. Martins,: ‘Efficient pseudopotentials for plane-wave calculations,’, Physical review B,, 1991, 43, pp.1993 22 M. Boroun, S. Abdolhosseini, and M. Pourfath,: ‘Separated and intermixed phases of borophene as anode material for lithium-Ion batteries,’, Journal of Physics D: Applied Physics,, 2019, 52, pp.245501 23 E. Zaremba and W. Kohn,: ‘Theory of helium adsorption on simple and noble-metal surfaces,’, Physical Review B,, 1977, 15, pp.1769
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ative to the horizontal and 45◦ rotated directions. From the Table, it can be found that, in most cases, the charge transfer in horizontal states is higher than vertical or oblique configuration. When the adenine molecule is in the vertical or oblique orientation, most charge transfer occurs at B and T sites. Also, it can be found that in each orientation, the lowest charge transfer occurs at H site. A comparison between horizontal and vertical orientation indicates that vertical orientation has lower adsorption energy, hence, it is more stable than the horizontal direction. But horizontal direction has higher charge transfer. According to adsorption energies provided in Table I, oblique(45◦ ) orientation, is less stable than vertical orientation, But its charge transfer in some sites increases and in other site decreases. These eight configurations reported in the table I have the lowest adsorption energy in comparison with all 27 configurations. The adsorption energy of adenine on MoS2 and B36 are -0.77eV and -0.84eV, respectively[8,18]. The quantities of adsorption energy of the χ3 phase of borophene compared to these materials indicate the high power of this substance for adsorption of an adenine molecule.
REFERENCES
Berland, S. D. Chakarova-Käck, V. R. Cooper, D. C. Langreth, and E. Schröder: ‘A van der Waals density functional study of adenine on
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HIGHLIGHTS
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In this paper, we investigate the adsorption of adenine molecules on a borophene sheet using a density functional theory. The adsorption geometry and optimum positions of the adenine molecule adsorption on the borophene sheet were determined in different directions. It was found that in some positions and directions of the borophene sheet, where the adsorption occurred physically, the energy of the adsorption and charge transfer was higher than the other cases where the chemical adsorption occurred. Results indicate the strong potential of borophene in adsorption of the adenine molecule, so this two-dimensional material could be a suitable candidate for future DNA sequencing devices.
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Physica E: Low-dimensional #PHYSE_2019_1582
Title: “Adsorption of Adenine Molecule on χ3 Borophene Nanosheets: A Density Functional Theory Study”
√ All authors declare no conflict of interest and have participated in (a) conception and design, or analysis and interpretation of the data; (b) drafting the article or revising it critically for important intellectual content; and (c) approval of the final version. √ This manuscript has not been submitted to, nor is under review at, another journal or other publishing venue.
√ The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript √ The following authors have affiliations with organizations with direct or indirect financial interest in the subject matter discussed in the manuscript: Author’s name
Affiliation
Iran
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Shirin Sabokdast Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Ashkan Horri Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Yavar T. Azar Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran Maryam Momeni Department of Electrical Engineering, Faculty of Engineering, Arak University, Arak, Mohammad bagher tavakoli
Department of Electrical Engineering, Arak Branch, Islamic Azad University,
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Arak, Iran
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According to International Committee of Medical Journal Editors (ICMJE): “An author is considered to be someone who has made substantive intellectual contributions to a published study. An author must take responsibility for at least one component of the work, should be able to identify who is responsible for each other component, and should ideally be confident in their co-authors’ ability and integrity. “ (available at: http://www.icmje.org/ethical_1author.html)
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Corresponding Author name and signiture: Ashkan Horri 8 January 2020
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