- Email: [email protected]
Polarons by nonlocal dynamical coherent potential method
ComputerPhysics Communications Computer PhysicsCommunications121-122 (1999) 669 www.elsevier.nl/locate/cpc
Abstract
Polarons by nonlocal dynamical coherent potential method S.V. Izvekov 1 Institute for Materials Research and Engineering, National University of Singapore, Singapore 119260
The nonlocal dynamical coherent potential approximation (NDCPA) is formulated to calculate a single-electron(exciton) Green's function of polaron due to the interaction of an electron(exciton) with lattice or molecular phonons. This approximation is an extension of the dynamical CPA [1]. The NDCPA provides an efficient means to calculate an approximate Green's function for a dynamical model of electrons(excitons) strongly coupled to optical or acoustical phonons, in the entire ranges of electron(exciton)-phonon coupling strengths and electron(exciton) transfer. The electron(exciton)-phonon coupling in the Hamiltonian may involve terms of any order with respect to the phonon operators. A set of recurrent equations is derived in the case of a system at finite temperatures, from which the coherent potential as a function of polaron energy E and momentum vector k can be obtained. A simple algorithm for the calculations of polaron spectra is obtained for the linear electron(exciton)phonon coupling, small electron(exciton) transfer, and with an assumption of only inelastic scatterings of electron(exciton) by phonons. The algorithm is modified if the elastic tz-phonon short-range scatterings are relevant. The numerical scheme provided by NDCPA has been applied to calculate the exciton absorption and emission spectra in the wide ranges of excitonic bandwidth, coupling constant, and temperature. © 1999 Elsevier Science B.V. All rights reserved.
References
"
[1] H. Sumi,L Phys. Soc. Jpn. 36 (1974) 770.
I [email protected]. 0010-4655/99/$ - see front matter © 1999 ElsevierScienceB.V. All rights reserved.
Abstract
Polarons by nonlocal dynamical coherent potential method S.V. Izvekov 1 Institute for Materials Research and Engineering, National University of Singapore, Singapore 119260
The nonlocal dynamical coherent potential approximation (NDCPA) is formulated to calculate a single-electron(exciton) Green's function of polaron due to the interaction of an electron(exciton) with lattice or molecular phonons. This approximation is an extension of the dynamical CPA [1]. The NDCPA provides an efficient means to calculate an approximate Green's function for a dynamical model of electrons(excitons) strongly coupled to optical or acoustical phonons, in the entire ranges of electron(exciton)-phonon coupling strengths and electron(exciton) transfer. The electron(exciton)-phonon coupling in the Hamiltonian may involve terms of any order with respect to the phonon operators. A set of recurrent equations is derived in the case of a system at finite temperatures, from which the coherent potential as a function of polaron energy E and momentum vector k can be obtained. A simple algorithm for the calculations of polaron spectra is obtained for the linear electron(exciton)phonon coupling, small electron(exciton) transfer, and with an assumption of only inelastic scatterings of electron(exciton) by phonons. The algorithm is modified if the elastic tz-phonon short-range scatterings are relevant. The numerical scheme provided by NDCPA has been applied to calculate the exciton absorption and emission spectra in the wide ranges of excitonic bandwidth, coupling constant, and temperature. © 1999 Elsevier Science B.V. All rights reserved.
References
"
[1] H. Sumi,L Phys. Soc. Jpn. 36 (1974) 770.
I [email protected]. 0010-4655/99/$ - see front matter © 1999 ElsevierScienceB.V. All rights reserved.