A four-dimensional potential energy surface for the Ar-D2O van der Waals complex: Bending normal coordinate dependence

In this paper, we report a four-dimensional potential energy surface (PES) of the Ar-D2O complex. The ab initio calculations are carried out by the coupled-cluster singles and doubles level with noniterative inclusion of connected triples [CCSD(T)] method with a large basis set supplemented with bond functions. The PES includes explicit dependence on the ν2 bending normal coordinate of Q2 the D2O molecule. Two vibrationally averaged PESs with D2O molecule in its ground and first ν2 excited vibrational states are generated by integrating over the Q2 normal coordinate. Based on these two PESs, the bound state energies are determined and used in the infrared spectra prediction. The theoretical frequencies for 104 infrared transitions of Π1(11)(ν2 = 1)←Σ0(00), Σ1(11)(ν2 = 1)←Σ0(00), Π1(10)(ν2 = 1)←Σ0(01), and Π1(01)(ν2 = 1)←Σ1(01) of Ar-D2O complex are in good agreement with the available experimental values.