A simple algorithm for the group theoretical classification of quantum states II. The case of molecular electronic states

This paper presents an extension of an algorithm recently published [Appl. Math. Comput. 133 (2002) 119] for the group theoretical classification of quantum states for molecular systems. In the original paper it was shown how this algorithm could be used to classify vibrational states. Here we show how to perform the classification of electronic states and discussed the advantage of using this technique over the traditional methods. It consists in finding the minimal set of symmetry operations needed to identify unequivocally the symmetry for each state and a direct calculation of the character of the representation expanded by the vector state. In order to illustrate the application of our method we show the classification of the electronic states for two different cluster systems of symmetries D4h and Ih.