THE MULTICONFIGURATION TIME-DEPENDENT HARTREE-FOCK METHOD BASED ON A CLOSED-SHELL-TYPE MULTICONFIGURATION SELF-CONSISTENT FIELD REFERENCE STATE AND ITS APPLICATION TO THE LIH MOLECULE

The linear response calculations in the multiconfiguration time-dependent Hartree-Fock (MCTDHF) approximation with a closed-shell-type MCSCF state as the time-independent reference state are discussed. The application to the LiH molecule with a small basis set ([4s2p1d/2s1p]) shows validity of our MCTDHF approach to the singlet ground state. Our MCSCF correlation energy is 97% of the total (= full CI) correlation energy and the MCTDHF excitation energies are in good agreements with the Δ full CI excitation energies. The Born-Oppenheimer potential energy curves for the lowest three singlet states of LiH and the corresponding vibrational level spacings, the transition moments, the oscillator strengths, and the frequency-dependent dipole polarizabilities are reported. All of these results imply the potentiality of our MCTDHF method for the future work with the larger basis set. One of such basis sets ([9sSp4d/8s7p1d]) is referentially used only at the single-configuration TDHF level, and the resultant near-Hartree-Fock polarizability and Thomas-Reiche-Kuhn sum rule is very promising. © 1990 American Institute of Physics.