ORTHOGONALLY SPIN-ADAPTED SINGLE-REFERENCE COUPLED-CLUSTER FORMALISM - LINEAR-RESPONSE CALCULATION OF STATIC PROPERTIES

An orthogonally spin-adapted coupled-cluster (CC) linear response (LR) method, to calculate first-order static properties of closed-shell systems, is formulated and implemented. Cluster operators are truncated at single and double excitations (CCSD-LR approach) and the explicit first-order CCSD-LR equations, in terms of molecular integrals and zeroth- and first-order cluster amplitudes, are given. Various aspects of the computer implementation of the CCSD-LR approach are discussed. In particular, the efficiency of the CCSD-LR approach is compared with corresponding finite field calculations. Advantages of using the LR approach are illustrated by calculating electrostatic multipole moments for CH2 and HF at equilibrium and displaced geometries. © 1995 American Institute of Physics.