Rayleigh light scattering from hydrogen-bonded dimers of small astrophysical molecules

High level ab initio calculations of the Rayleigh scattering activities of the hydrogen-bonded dimers of formic acid (HCOOH), nitrosyl hydride (HNO), and hydrogen cyanide (HCN) molecules have been performed. All these molecules have already been detected in interstellar space and are of great importance from the astrochemical point of view. The geometries of the homo- and hetero-dimers have been optimized using HartreeFock and second-order Muller-Plesset perturbation theory. Dipole moment, mean dipole polarizability, and polarizability anisotropy have been calculated utilizing Pople-type 6-311++G(d,p) and Dunning's aug-cc-pVDZ basis sets for all the complexes. The polarizabilities are then used to calculate and analyze the Rayleigh scattering parameters. The results for the dimers, HCN...HCN, HCOOH...HCOOH, HNO...HNO, HCN...HCOOH, HCN...HNO, and HNO...HCOOH are compared with those of the isolated molecules, HCN, HCOOH, and HNO to see the effect of hydrogen bond formation on the molecular interaction with radiation. (c) 2011 Wiley Periodicals, Inc.