The fragment molecular orbital (FMO) method is introduced into a Metropolis Monte Carlo search to find local minima on the potential energy surface.   Metropolis Monte Carlo implementations, traditionally, move molecules as rigid groups and thus restrict the search of the potential energy surface.   To address this limitation a new multilayer Monte Carlo algorithm is proposed.  As before, fragments are first moved rigidly and then a second Monte Carlo search is carried out on the fragment within the electro static potential of the rest of the system.  This second Monte Carlo search on the internal coordinates of the fragment is carried out with relatively little computational cost as the individual fragment size is much smaller than the rest of the system.  To test the algorithm, the minima of increasing cluster size of ethanol (n=2-5) were located and compared to geometry optimizations.

Multilayer Monte Carlo: An ab initio, a FMO flexible molecule method

244th National Meeting (2012)

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