In this chapter ve shall discuss the calculation of potential energy associated vith molecular conforaations. Raving obtained cartesian atoaic coordinates defining conforaations. and lists of intraao- cular interactions, as described in Chapter 3, ve are ready to calculate a quantity which in the chemical literature is known as the total aolecular potential energy or the conforaational, steric, strain or intraaolecular energy. ~he conformational energy of a aolecule can be expressed as a function , of all internal coordinates and interatoaic distances, or as a function of atoaic positions...