A Four-dimensional Potential Energy Surface And Predicted Infrared Spectra For The Ne-D₂O Van Der Waals Complexe In The ν₂ Bending Region Of D₂O

Van der Waals complexes exists in many of the chemical process and physical phenomena.The complexes which consisting of a rare gas（Rg）atom and a molecule are model systems to study intermolecular interactions,and thus have been extensively studied.This paper presents a four-dimensional potential energy surface and predictions of infrared spectra of Ne-D₂O complex.The main results we have obtained of this paper are as follows:（1）ab initio calculations are carried out by the coupled-cluster single and double with non-iterative treatment of triple excitations [CCSD（T）]level,using a large basis set aug-cc-pVQZ and supplemented bond functions（3s3p2d1f）.A total of 11466 grid-points are chosen for the potential energy calculations,including the v₂ bending normal mode coordinate of D₂O monomer.The discrete values at those grids are further used to construct the four-dimensional potential energy surface for Ne-D₂O system by the moving interpolation method and polynomial interpolation technique.（2）Adopting the vibrationally averaged approximation,we integrate over the normal coordinate variable Q₂ in the four-dimensional potential energy surface,and obtain two vibrationally averaged potential V₀₀ and V₁₁.The vibrationally averaged V₀₀ PES has a global minimum with a well depth of-63.67cm^-1 at R=3.223?,φ =0.0° and θ=105.2°.The vibrationally averaged V₁₁ PES has a global minimum at R=3.228?,φ=0.0° and θ=104.85° with a well depth of-65.09471cm^-1,slightly lower than V₀₀ PES.We further found that the V₁₁ PES has a similar structure as V₀₀ PES.The potential energy surface shows that it’s more stable when the Ne atom is located in the plane of the D₂O molecule.（3）According to the two vibrationally averaged potential V₀₀ and V₁₁ of the system,a FORTRAN program is developed to calculate the rovibrational energy levels.The predicted infrared spectra are given.The theoretical frequencies for 57 experimentally infrared transitions of П(1₁₁,ν2=1)←Σ0₀₀,Σ(1₁₁,ν₂=1)←Σ0₀₀ and n=1,Σ(0₀₀,ν₂=1)←Σ0₀₀ of Ne–D2O complex are calculated and in a better agreement with the corresponding experimentally observed values.