- Email: [email protected]
Recent advances in molecular modelling of materials with applications to polymers, semiconductors, metal alloys and catalysts
M e _ _ M e
O, ......Rh ......' 0 ~ x
x ll inum complexes found in the literature. Effective core potentials were used for heavy elements, extending to and including the l s atomic orbitals for C, N, O, and F, 2p for S, and 3d for Rh; and triple zeta plus polarization basis sets for all atoms. The calculated distortions we find in the metal coordination sphere differ from those predicted in our earlier work t in which we used a simpler model and method. These differences can, however, be explained by the unsymmetrical nature of the olefins in the current study. Good agreement has been found between experiment and theory, with only small discrepancies between experimental and calculated bond lengths and angles. An interesting correlation between the geometry and the bonding interactions in the substituted olefins has been noted and will be explained along with its relevance to catalysis.
References 1. Brown, J. M., Guiry, P. J., Hursthouse, M. B., Karalulov. S. and Price, D. W. Tel. Asymm. 5 (1994) 561. 2. Baerends, E. J., Ellis, D. E. and Ros, P. Chem. Phys. 2 (1973) 41.
Session 2: Fluids and Surfactants Session Chair: D. Fincham
Simulating the Adsorption in Porous Media: From Zeolites to Well-Bores By Berend Smit, Shell Research and Technology Centre. Amsterdam P.O. Box 38000 1030 BN Amsterdam. TIlE NETHERLANDS
The adsorption of molecules in porous media is of importance in processes ranging from catalysis using zeolites to swelling of clays in oil and gas production when drilling wells through mudrocks. In these applications it is important to obtain a detailed molecular understanding of the adsorption mechanisms. It is shown that special techniques are required to simulate these type of systems. The use of these simulation techniques is illustrated with some examples: the adsorption of hydrocarbons in zeolites and the swelling behavior of sodium-montmorillonite.
Computer Simulation of Polymer-Colloid Mixtures By D. Frenkel. FOM Institute for Atomic and Molecular Physics, Amsterdam, THE NETHERLANDS
Mixtures of polymers and colloids play an important role in many industrial processes. In order to model the properties of such mixtures, it is important to understand the nature of the interactions that occur in such mixtures. In my talk, I will focus on mixtures of colloids and non-adsorbing polymers. In such systems, the stability of the colloidal dispersion is determined by purely entropic forces. I shall discuss numerical simulations of such polymer colloid mixtures. Moreover, I shall indicate how such simulations shed light on seemingly unrelated problems, such as the hightemperature behavior of C60 and the possibility to crystallize globular proteins.
Session 3: Polymers and Materials Session Chairs: W. J. Briels and H. Toulhoat
Recent Advances in Molecular Modelling of Materials with Applications to Polymers, Semiconductors, Metal Alloys and Catalysts By William A. Goddard.lll, Charles and Mary Ferkel Professor of Chemistry and
Applied Physics, and Director, Materials and Process Simulation Center (MSC) California Institute of Technology Pasadena, California 91125 USA
We will discuss some of the recent advances in techniques for large scale atomistic simulations of materials: 1. GDS-DFT: dual space density functional theory using Gaussian basis functions for quantum mechanics on surfaces with full Periodic Boundary Conditions; 2. MPSim: large scale (millions of atoms per unit cell) molecular dynamics simulations of molecules and solids using massively parallel multiprocessor computers; 3. PS-GVB: pseudospectral methodology for ab initio quantum chemical calculations of large molecules (Local MP2, solvation, hyperpolarizabilities). 4. CC-BB-MC: continuous configuration Boltzmann Biased Monte Carlo for calculating thermodynamics properties of polymer mixtures. We will discuss recent progress in applying these melhods to predictions on problems such as: a. a new metallocene catalyst for ot-olefin polymerization b. mechanism for Ru ring opening metathesis polymerization (ROMP) catalysts c. growth and properties of semiconductor thin films (GaN or Hg I -xCdxTe) d. nonlinear optical properties of organics (saturation of y for polyacetylenes) e. encapsulation o1"molecules in dendritic polymers f. gas diffusion in polymers g: mechanism for drug action on rhino viruses (responsible for common cold) h. protein folding using CC-BB-MC i. mechanism of corrosion inhibitors for oil pipelines j. mechanism of wear inhibitors for automobile engines k. demulsifiers for asphaltene/oil/ water systems
J. Mol. Graphics Mod., 1996, Vol. 14, December
379
O, ......Rh ......' 0 ~ x
x ll inum complexes found in the literature. Effective core potentials were used for heavy elements, extending to and including the l s atomic orbitals for C, N, O, and F, 2p for S, and 3d for Rh; and triple zeta plus polarization basis sets for all atoms. The calculated distortions we find in the metal coordination sphere differ from those predicted in our earlier work t in which we used a simpler model and method. These differences can, however, be explained by the unsymmetrical nature of the olefins in the current study. Good agreement has been found between experiment and theory, with only small discrepancies between experimental and calculated bond lengths and angles. An interesting correlation between the geometry and the bonding interactions in the substituted olefins has been noted and will be explained along with its relevance to catalysis.
References 1. Brown, J. M., Guiry, P. J., Hursthouse, M. B., Karalulov. S. and Price, D. W. Tel. Asymm. 5 (1994) 561. 2. Baerends, E. J., Ellis, D. E. and Ros, P. Chem. Phys. 2 (1973) 41.
Session 2: Fluids and Surfactants Session Chair: D. Fincham
Simulating the Adsorption in Porous Media: From Zeolites to Well-Bores By Berend Smit, Shell Research and Technology Centre. Amsterdam P.O. Box 38000 1030 BN Amsterdam. TIlE NETHERLANDS
The adsorption of molecules in porous media is of importance in processes ranging from catalysis using zeolites to swelling of clays in oil and gas production when drilling wells through mudrocks. In these applications it is important to obtain a detailed molecular understanding of the adsorption mechanisms. It is shown that special techniques are required to simulate these type of systems. The use of these simulation techniques is illustrated with some examples: the adsorption of hydrocarbons in zeolites and the swelling behavior of sodium-montmorillonite.
Computer Simulation of Polymer-Colloid Mixtures By D. Frenkel. FOM Institute for Atomic and Molecular Physics, Amsterdam, THE NETHERLANDS
Mixtures of polymers and colloids play an important role in many industrial processes. In order to model the properties of such mixtures, it is important to understand the nature of the interactions that occur in such mixtures. In my talk, I will focus on mixtures of colloids and non-adsorbing polymers. In such systems, the stability of the colloidal dispersion is determined by purely entropic forces. I shall discuss numerical simulations of such polymer colloid mixtures. Moreover, I shall indicate how such simulations shed light on seemingly unrelated problems, such as the hightemperature behavior of C60 and the possibility to crystallize globular proteins.
Session 3: Polymers and Materials Session Chairs: W. J. Briels and H. Toulhoat
Recent Advances in Molecular Modelling of Materials with Applications to Polymers, Semiconductors, Metal Alloys and Catalysts By William A. Goddard.lll, Charles and Mary Ferkel Professor of Chemistry and
Applied Physics, and Director, Materials and Process Simulation Center (MSC) California Institute of Technology Pasadena, California 91125 USA
We will discuss some of the recent advances in techniques for large scale atomistic simulations of materials: 1. GDS-DFT: dual space density functional theory using Gaussian basis functions for quantum mechanics on surfaces with full Periodic Boundary Conditions; 2. MPSim: large scale (millions of atoms per unit cell) molecular dynamics simulations of molecules and solids using massively parallel multiprocessor computers; 3. PS-GVB: pseudospectral methodology for ab initio quantum chemical calculations of large molecules (Local MP2, solvation, hyperpolarizabilities). 4. CC-BB-MC: continuous configuration Boltzmann Biased Monte Carlo for calculating thermodynamics properties of polymer mixtures. We will discuss recent progress in applying these melhods to predictions on problems such as: a. a new metallocene catalyst for ot-olefin polymerization b. mechanism for Ru ring opening metathesis polymerization (ROMP) catalysts c. growth and properties of semiconductor thin films (GaN or Hg I -xCdxTe) d. nonlinear optical properties of organics (saturation of y for polyacetylenes) e. encapsulation o1"molecules in dendritic polymers f. gas diffusion in polymers g: mechanism for drug action on rhino viruses (responsible for common cold) h. protein folding using CC-BB-MC i. mechanism of corrosion inhibitors for oil pipelines j. mechanism of wear inhibitors for automobile engines k. demulsifiers for asphaltene/oil/ water systems
J. Mol. Graphics Mod., 1996, Vol. 14, December
379