Kinetic Energy Operator for Linear A2B2 Type Molecules in Polyspherical Nonorthogonal Internal Coordinates

The form of the vibrational-rotational operator of kinetic energy for linear symmetric molecules of the A(2)B(2) type in polyspherical nonorthogonal internal coordinates (bond lengths and angles between bonds) is obtained. Nonorthogonal coordinates have advantages in calculating the wave functions of heavy linear molecules, for example, C2F2 and C2Cl2; they also simplify the calculation of the intensity of vibrational-rotational spectral lines of molecules belonging to this type. This work is a continuation of work [1], in which the form of the kinetic energy operator in orthogonal coordinates was obtained. To verify the expressions derived, the lower vibrational-rotational energy levels of the acetylene molecule are calculated.