CCL: How to calculate the independent degrees of freedom of a molecule?



Hello everyone:
 
For a nonlinear N-atom molecule there are 3N-6 internal degrees of freedom, of course.  However, for a point group-constraint molecule, such as C2v H2O, there are only 2 independent degrees of freedom. So, is there a systematic way to determine the number and the contents of independent degrees of freedom of an arbitarily symmetry-constraint molecule? I heard that some knowledge like Polya theorem are requied, but I am not sure. It will be better if some reviews can be reccommended.
 
Thank you in advance. Any suggestions will be appreciated.
 
Best regards!
 
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Jun Zhang (coolrainbow=-=yahoo.cn)
Computational Chemistry Group
No.94, Weijinlu
Nankai University
Tianjin, China