TY - JOUR
T1 - Second-order polarization propagator approximation with coupled-cluster singles and doubles amplitudes - SOPPA(CCSD): the polarizability and hyperpolarizability of Li-
AU - Sauer, Stephan P. A.
PY - 1997
Y1 - 1997
N2 - A new modification of the second-order polarization propagator approximation (SOPPA) is presented. In the new method, called SOPPA(CCSD), all first-order Møller - Plesset doubles and second-order Møller - Plesset singles correlation coefficients are replaced with the corresponding coupled-cluster singles and doubles (CCSD) T2 and T1 amplitudes. This is in contrast to the earlier coupled-cluster polarization propagator approximation (CCSDPPA) in which only one of the doubles correlation coefficients was replaced in the unrelaxed second-order density matrix. The importance of this modification is investigated for the dipole polarizability, dipole oscillator strength sum rules and second hyperpolarizability of Li-, which is known to be a difficult case for perturbative methods. The SOPPA(CCSD) values are compared with previous and new full CI results for the same basis sets.
AB - A new modification of the second-order polarization propagator approximation (SOPPA) is presented. In the new method, called SOPPA(CCSD), all first-order Møller - Plesset doubles and second-order Møller - Plesset singles correlation coefficients are replaced with the corresponding coupled-cluster singles and doubles (CCSD) T2 and T1 amplitudes. This is in contrast to the earlier coupled-cluster polarization propagator approximation (CCSDPPA) in which only one of the doubles correlation coefficients was replaced in the unrelaxed second-order density matrix. The importance of this modification is investigated for the dipole polarizability, dipole oscillator strength sum rules and second hyperpolarizability of Li-, which is known to be a difficult case for perturbative methods. The SOPPA(CCSD) values are compared with previous and new full CI results for the same basis sets.
U2 - 10.1088/0953-4075/30/17/007
DO - 10.1088/0953-4075/30/17/007
M3 - Journal article
SN - 0953-4075
VL - 30
SP - 3773
EP - 3780
JO - Journal of Physics B: Atomic, Molecular and Optical Physics
JF - Journal of Physics B: Atomic, Molecular and Optical Physics
IS - 17
ER -