M3C: A Computational Approach to Describe Statistical Fragmentation of Excited Molecules and Clusters

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Theory and Computation, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see [insert ACS Articles on Request author-directed link to Published Work, see http://pubs.acs.org/doi/abs/10.1021/acs.jctc.6b00984
The Microcanonical Metropolis Monte Carlo method, based on a random sampling of the density of states, is revisited for the study of molecular fragmentation in the gas phase (isolated molecules, atomic and molecular clusters, complex biomolecules, etc.). A random walk or uniform random sampling in the configurational space (atomic positions) and a uniform random sampling of the relative orientation, vibrational energy, and chemical composition of the fragments is used to estimate the density of states of the system, which is continuously updated as the random sampling populates individual states. The validity and usefulness of the method is demonstrated by applying it to evaluate the caloric curve of a weakly bound rare gas cluster (Ar13 ), to interpret the fragmentation of highly excited small neutral and singly positively charged carbon clusters (Cn , n = 5,7,9 and Cn+, n = 4,5) and to simulate the mass spectrum of the acetylene molecule (C2H2 )
Work was supported by the MINECO projects FIS2013-42002-R and CTQ2013-43698-P the CAM project NANOFRONTMAG-CM ref S2013/MIT-2850S, and the European COST Action CM1204 XLIC. S.D.-T. gratefully acknowledges the Ramon y Cajal program of the Spanish MINECO. Financial support from the Spanish Ministry of Economy and Competitiveness, through The Maria de Maeztu Programme for Units of Excellence in R&D (MDM-2014-0377) is acknowledged