摘要：A novel method which makes full use of point groups including Abeian and nonAbelian groups is presented. The key point for this method is the definition of a kind of newsymmetry moecular orbitals (SMOs). Any group element in a moecular point group willtransform one SMO to another equlvalent SMO and no mixture among SMCh exists. The unique feature will be kept for one or two - electron integrals as well as the Slater determinantsconstructed using SMCh. Consequently, the character integrals and character detendnants(CDs) can be selected according to some simple rules. Based on this method, a preliminarycharacter single and doubly excited single reference CI (CD - SR - CISD) program is developed, and pilot calculations are performed and compared with GAUSSIAN - 94.For thehigh symmetry point group models and linear molecules our CD - CISD program costs lessCPU - time than G94 - CISD and the storage demand of CD - CISD is also remarkably alleviated.
