Linear-scaling implementation of molecular response theory in self-consistent field electronic-structure theory.
A linear-scaling implementation of Hartree-Fock and Kohn-Sham self-consistent field theories for the calculation of frequency-dependent molecular response properties and excitation energies is presented, based on a nonredundant exponential parametrization of the one-electron density matrix in the atomic-orbital basis, avoiding the use of canonical orbitals. The response equations are solved iteratively, by an atomic-orbital subspace method equivalent to that of molecular-orbital theory. Important features of the subspace method are the use of paired trial vectors (to preserve the algebraic structure of the response equations), a nondiagonal preconditioner (for rapid convergence), and the generation of good initial guesses (for robust solution). As a result, the performance of the iterative method is the same as in canonical molecular-orbital theory, with five to ten iterations needed for convergence. As in traditional direct Hartree-Fock and Kohn-Sham theories, the calculations are dominated by the construction of the effective Fock/Kohn-Sham matrix, once in each iteration. Linear complexity is achieved by using sparse-matrix algebra, as illustrated in calculations of excitation energies and frequency-dependent polarizabilities of polyalanine peptides containing up to 1400 atoms.
Coriani
Sonia
S
Dipartimento di Scienze Chimiche, Università degli Studi di Trieste, Via Licio Giorgieri 1, I-34127 Trieste, Italy.
Høst
Stinne
S
Jansík
Branislav
B
Thøgersen
Lea
L
Olsen
Jeppe
J
Jørgensen
Poul
P
Reine
Simen
S
Pawłowski
Filip
F
Helgaker
Trygve
T
Sałek
Paweł
P