MSINDO-sCIS: A New Method for the Calculation of Excited States of Large Molecules.

摘要: Theoretical background, parametrization, and performance of the semiempirical configuration interaction singles (CIS) method MSINDO-sCIS designed for calculation optical spectra large organic molecules are presented. The CIS Hamiltonian is modified by scaling Coulomb exchange integrals a correction. For recently proposed benchmark set 28 medium-sized molecules, vertical excitation energies singlet triplet states calculated statistically evaluated. A full reparameterization MSINDO both ground excited state properties was necessary. results reparameterized compared to currently best states, OM3-CISDTQ, other standard methods, such as MNDO INDO/S. mean absolute deviation with respect theoretical estimates (TBEs) 0.44 eV, comparable OM3 but significantly smaller than computational effort strongly reduced OM3-CISDTQ OM3-MRCISD, since only single excitations taken into account. Higher implicitly included parametrization an empirical correction term. By application Davidson-Liu block diagonalization method, high efficiency achieved. Furthermore, it demonstrated that correctly describes charge-transfer (CT) represent problem time-dependent density functional theory (TD-DFT) methods.