CALCULATION OF FREQUENCY-DEPENDENT POLARIZABILITIES USING COUPLED-CLUSTER RESPONSE THEORY

Coupled-cluster singles and doubles linear response (CCLR) calculations have been presented for frequency-dependent dipole polarizabilities and the results compared with the results from a CI-like approach to the equation of motion (EOMCC). The frequency-dependent polarizabilities are similar in the two approaches for single molecule calculations on small systems. However, the CCLR approach gives size-extensive polarizabilities, whereas the EOMCC approach does not. EOMCC calculations can therefore give unphysical polarizabilities, e.g. EOMCC calculations on a sequence of non-interacting LiH systems gave a negative polarizability for 20 or more non-interacting LiH systems. The CCLR approach is shown to be an attractive ''black box'' approach for the calculation of accurate frequency-dependent polarizabilities.