EXTRAPOLATION OF REAL-SPACE QUANTUM-CHEMICAL CALCULATIONS FROM FINITE-SIZE SUPER CELLS TO THE IDEAL INFINITE SYSTEM .1. THEORY

Citation
V. Nolting et Ws. Verwoerd, EXTRAPOLATION OF REAL-SPACE QUANTUM-CHEMICAL CALCULATIONS FROM FINITE-SIZE SUPER CELLS TO THE IDEAL INFINITE SYSTEM .1. THEORY, International journal of quantum chemistry, 52(6), 1994, pp. 1273-1285
Citations number
26
Categorie Soggetti
Chemistry Physical
ISSN journal
00207608
Volume
52
Issue
6
Year of publication
1994
Pages
1273 - 1285
Database
ISI
SICI code
0020-7608(1994)52:6<1273:EORQCF>2.0.ZU;2-T
Abstract
A method is proposed how to calculate the correct density matrix of an infinite polymeric chain from that of a standard finite supercell cal culation. The density matrix of the finite supercell is transformed in to k-space for all k-values allowed by the periodic boundary condition s. The k-dependent matrices are then unitarily transformed, with each unitary matrix being represented by a set of complex rotation matrices . It is shown that the corresponding angles can be interpolated and ex trapolated toward the zone boundaries in a straightforward manner and that this extrapolation can be done from any finite supercell with rea sonable accuracy. This gives rise to an infinite system density matrix for which all fundamental properties are guaranteed by construction. This infinite system density matrix may be used to construct a correct ed density matrix for the finite supercell calculation. (C) 1994 John Wiley & Sons, Inc.