Approximate ab initio calculations of polarizabilities via the excitation scheme

The excitation scheme is explored as an alternative to the more usual coupled Hartree-Fock and similar analytical derivative calculations of polarizabilities and other molecular properties. The scheme can be implemented more easily and requires only a small fraction of the computer time and memory needed for conventional calculations. The accuracy of the two approaches is fully comparable for calculations done with incomplete basis sets. This is documented on computations of polarizabilities and magnetic susceptibilities of water, pyridine and pyrimidine molecules performed at the HF and DFT (B3LYP) levels.