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
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.