Experimental designs for finding stationary points and for computing force constant matrix

We use an experimental design method for computing a local quadratic form which is adequate to find stationary points and to evaluate the force constant matrix on a k ‐dimensional potential energy hypersurface. Two types of designs are particularly discussed: the composite and the Doehiert's plane. We give examples for illustrating the methodology. Some thermodynamical properties are deduced from our results. Such a method may be used with every type of theoretical calculations ( SCF or CI ) and with any program without modification.