Low‐energy structures of benzene clusters with a novel accurate potential surface |
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Authors: | M. Bartolomei F. Pirani J. M. C. Marques |
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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 |
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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 clusters may be obtained by summing up over all pair potentials. We apply an evolutionary algorithm (EA) to discover the lowest‐energy structures of clusters (for ), 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 and 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 isomers show S6 and C3 symmetry, respectively, which is compatible with the experimental results available in the literature. The 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. |
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Keywords: | ab initio calculations semiempirical potential model global optimization evolutionary algorithms low‐energy structures benzene clusters |
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