The dipole moment, polarizabilities and hyperpolarizabilities of Ne, Be, BH, CH+, CO and NNO have been determined using the coupled-cluster and Brueckner coupled-cluster methods. The effect of orbital relaxation on these properties has been investigated implicitly, by carrying out singles and doubled coupled-cluster (CCSD) calculations with and without field relaxed SCF orbitals and explicitly through carrying out Brueckner doubles (BCCD) calculations. The effect of the connected triple excitations has been considered in the methods CCSD(T) and BCCD(T). The results show that allowing the SCF orbitals to relax in the presence of the field can make a significant difference to the CCSD properties. It has also been found that CCSD with field relaxed SCF orbitals and BCCD give similar results. © 1993.
Comparison of coupled-cluster and Brueckner coupled-cluster calculations of molecular properties
Koch, Henrik;
1993
Abstract
The dipole moment, polarizabilities and hyperpolarizabilities of Ne, Be, BH, CH+, CO and NNO have been determined using the coupled-cluster and Brueckner coupled-cluster methods. The effect of orbital relaxation on these properties has been investigated implicitly, by carrying out singles and doubled coupled-cluster (CCSD) calculations with and without field relaxed SCF orbitals and explicitly through carrying out Brueckner doubles (BCCD) calculations. The effect of the connected triple excitations has been considered in the methods CCSD(T) and BCCD(T). The results show that allowing the SCF orbitals to relax in the presence of the field can make a significant difference to the CCSD properties. It has also been found that CCSD with field relaxed SCF orbitals and BCCD give similar results. © 1993.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
