A NEW TABLE-DIRECT CONFIGURATION-INTERACTION METHOD FOR THE EVALUATION OF HAMILTONIAN MATRIX-ELEMENTS IN A BASIS OF LINEAR-COMBINATIONS OF SPIN-ADAPTED FUNCTIONS

Citation
S. Krebs et Rj. Buenker, A NEW TABLE-DIRECT CONFIGURATION-INTERACTION METHOD FOR THE EVALUATION OF HAMILTONIAN MATRIX-ELEMENTS IN A BASIS OF LINEAR-COMBINATIONS OF SPIN-ADAPTED FUNCTIONS, The Journal of chemical physics, 103(13), 1995, pp. 5613-5629
Citations number
42
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
ISSN journal
00219606
Volume
103
Issue
13
Year of publication
1995
Pages
5613 - 5629
Database
ISI
SICI code
0021-9606(1995)103:13<5613:ANTCMF>2.0.ZU;2-D
Abstract
A new table-direct CI (TDCI) scheme based on the table CI method for t he direct computation of Hamiltonian matrix elements whose basis funct ions are linear combinations of spin-adapted functions psi(alpha) is p resented, in which the explicit calculation and storage of the Hamilto nian matrix H in the basis {psi(alpha)} is avoided. Two algorithms are provided for the matrix element evaluation; (i) within the iterative Davidson diagonalization procedure of H and (ii) within the individual ized configuration selection scheme of Buenker and Peyerimhoff, as inc luded in the MRD-CI program of these authors. The new algorithm is emp loyed to compute the equilibrium structural parameters of the lowest X (2)A(1) and A B-2(2) states of NO2, solving secular equations of dime nsion 190 000 spin-adapted functions (384 000 determinants, 32 000 con figurations), as well as the T-e value for the corresponding transitio n. (C) 1995 American Institute of Physics.