AB INITIO ANALYTIC CUBIC FORCE CONSTANT IN GENERAL COORDINATE SPACE USING SPHERICAL GAUSSIAN FUNCTION

The Floating Spherical Gaussian Orbital (FSGO) closed-shell energy analytic third derivative with respect to nuclear displacement is presented here. In order to save computational time, the formulas for the third derivative of electron nuclear attraction are written in terms of original integrals. Although the formulas were presented in general for any type of application, the FSGO method is applied to H₂O and CH₂ molecules in singlet ground electronic state. Besides the accuracy of analytical derivative, the saving in computational time is significant.