DIPOLE-MOMENT AND POLARIZABILITY FUNCTIONS OF AMMONIA - A LINEAR-RESPONSE COUPLED-CLUSTER STUDY

The recently developed orthogonally spin-adapted linear-response coupl ed-cluster theory with singly and doubly excited clusters (LRCCSD) has been employed to calculate the dipole moment and parallel polarizabil ity functions of ammonia over a wide range of values of the inversiona l and symmetric stretch coordinates. Using the eigenstates of the expe rimentally derived nonrigid invertor Hamiltonian of ammonia and the LR CCSD property functions, the transition dipole moments between several low-lying inversional states and the rovibrationally averaged paralle l polarizabilities for several values of the inversional quantum numbe r have been evaluated. The calculated transition dipole moments and ro vibrationally averaged polarizabilities have been found to be in excel lent agreement wi th the available experimental and theoretical data, indicating the suit ability of the nb initio LRCCSD theory for such ca lculations. The LRCCSD transition dipole moments are far more accurate than all previously obtained nb initio values.