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Low‐energy structures of benzene clusters with a novel accurate potential surface
Authors:M. Bartolomei  F. Pirani  J. M. C. Marques
Affiliation:1. Consejo Superior de Investigaciones Científicas (IFF‐CSIC), Instituto de Física Fundamental, Madrid, Spain;2. Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Italy;3. Departamento de Química, Universidade de Coimbra, Coimbra, Portugal
Abstract:The benzene‐benzene (Bz‐Bz) interaction is present in several chemical systems and it is known to be crucial in understanding the specificity of important biological phenomena. In this work, we propose a novel Bz‐Bz analytical potential energy surface which is fine‐tuned on accurate ab initio calculations in order to improve its reliability. Once the Bz‐Bz interaction is modeled, an analytical function for the energy of the urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0001 clusters may be obtained by summing up over all pair potentials. We apply an evolutionary algorithm (EA) to discover the lowest‐energy structures of urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0002 clusters (for urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0003), and the results are compared with previous global optimization studies where different potential functions were employed. Besides the global minimum, the EA also gives the structures of other low‐lying isomers ranked by the corresponding energy. Additional ab initio calculations are carried out for the low‐lying isomers of urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0004 and urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0005 clusters, and the global minimum is confirmed as the most stable structure for both sizes. Finally, a detailed analysis of the low‐energy isomers of the n = 13 and 19 magic‐number clusters is performed. The two lowest‐energy urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0006 isomers show S6 and C3 symmetry, respectively, which is compatible with the experimental results available in the literature. The urn:x-wiley:01928651:media:jcc24201:jcc24201-math-0007 structures reported here are all non‐symmetric, showing two central Bz molecules surrounded by 12 nearest‐neighbor monomers in the case of the five lowest‐energy structures. © 2015 Wiley Periodicals, Inc.
Keywords:ab initio calculations  semiempirical potential model  global optimization  evolutionary algorithms  low‐energy structures  benzene clusters
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