Correlation function quantum Monte Carlo studies of rovibrational excited states in molecules

In this paper we review the correlation function quantum Monte Carlo (CFQMC ) method. We describe the functional forms and the optimization of trial ba sis functions used to treat the vibrational and rotational motions. We disc uss selected applications to di-, tri- and tetra-atomic molecules. Our main goal is to discuss the potentiality of the CFQMC method in the study of ro vibrational excited states of polyatomic molecules. In particular, we focus our discussion on the generation of the trial basis functions for ground a nd excited states, and the guiding function used to perform the multidimens ional integral sampling required by the method.