Variation of the second hyperpolarisability of (HF)n induced by changes in the structure. A comparative study

Abstract

The second hyperpolarisability, γ, of (HF)_n, where n= 6, 8, and the interaction hyperpolarisability, Δγ, of (HF)₂ are computed by employing ab initio and semiempirical techniques. The results demonstrate the cooperative character of the intermolecular interactions between the H-bonded hydrogen fluoride molecules and their considerable effect on the second hyperpolarisability. The results also show that remarkable variations in Δγ and γ may be induced by a change in the shape of the HF cluster.