A detailed investigation on the global minimum structures of mixed rare‐gas clusters: Geometry, energetics, and site occupancy

Marques, Jorge M. C.; Pereira, Francisco B.

doi:10.1002/jcc.23161

Cited by 17 publications

(14 citation statements)

References 51 publications

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“…Due to the additional β parameter, the ILJ function becomes more flexible than the traditional LJ model. Hence, the overestimation of the short range repulsion and of long‐range attraction by the LJ potential is corrected in the ILJ function, which appears to be important especially when several partners are involved in the formation of aggregates; for instance, it is sufficient to modify the structure of binary rare‐gas clusters …”

Section: Computational Proceduresmentioning

confidence: 99%

Low‐energy structures of benzene clusters with a novel accurate potential surface

2015

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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 Bzn clusters may be obtained by summing up over all pair potentials. We apply an evolutionary algorithm (EA) to discover the lowest-energy structures of Bzn clusters (for n=2-25), 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 Bz3 and Bz4 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 Bz13 isomers show S6 and C3 symmetry, respectively, which is compatible with the experimental results available in the literature. The Bz19 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.

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Section: Computational Proceduresmentioning

confidence: 99%

Low‐energy structures of benzene clusters with a novel accurate potential surface

2015

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“…According to this endeavor, we have developed in the last years unbiased evolutionary algorithms (EAs) that seek the global minimum structure of atomic [9][10][11][12][13] and molecular [14] clusters; these algorithms have been successfully applied to discover the global minimum of several atomic and molecular aggregates (see Refs. [15,16] and references therein). Clearly, EAs are among the best methods for global geometry optimization of clusters, and they are known to over perform random search algorithms, like the so-called big-bang method [17], as we have shown in a recent work [18,19].…”

Section: Introductionmentioning

confidence: 99%

New insights on lithium-cation microsolvation by solvents forming hydrogen-bonds: Water versus methanol

Llanio-Trujillo

Marques

Pereira

2013

Computational and Theoretical Chemistry

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This investigation uses a recent methodology, essentially based on our evolutionary algorithm (EA) to get new insights about the energetics and structure of the first solvation shells of lithium ion in polar solvents that form important hydrogen bonds. We employed the EA to search for the low-energy structures of the Li + (H 2 O) n and Li + (CH 3 OH) n clusters (with n 6 20) as modeled by commonly used rigid nonpolarizable force-field potentials. Particular emphasis is given to the characterization of the putative global minima; for Li + (H 2 O) 17 , the EA discovered a new global minimum with five water molecules directly coordinating the ion. Smaller-size clusters were, then, re-optimized by employing electronicstructure methods, namely, DFT (with the B3LYP functional and both the 6-31+G ⁄ and 6-311+G ⁄⁄ basis sets) and MP2 (with the aug-cc-pVDZ basis set). In the case of Li + (H 2 O) n , the ab initio global minimum structures are similar to those obtained with the EA up to n = 10. However, for n = 17, the structure of the global minimum discovered by the EA is different from the lowest-energy cluster obtained after re-optimization at the MP2/augcc-pVDZ level of theory. Such energy reorder may be attributed to the water-water interaction. As for the Li + (CH 3 OH) n clusters, the re-optimization process leads more often to a reorder in the energy of the minimum structures. Thus, forfluxional clusters like the Li + (CH 3 OH) n ones that show a huge number of stationary configurations within a small energy window, it is mandatory to carefully choose various structures, besides the global minimum, to be re-optimized at the ab initio or DFT levels. Due to the difficulty on choosing adequate departing structures by the usually employed chemical intuition, we noticed that some low-energy minima (including the global one) of even small Li + (CH 3 OH) n clusters were missed in literature. We showcase this problem in the Li + (CH 3 OH) 6 cluster, whose vibrational frequencies in the CO stretching region and corresponding infrared intensities were calculated at the DFT level of theory and compared with previously reported results.

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“…They are also interesting because catalytic properties of such clusters depend on the composition and structure. Comparatively little work has been done on the mixed clusters [150,151,152] as the search space is dramatically enlarged with the inclusion of more atom types. Mixed LJ clusters of widely varying compositions offer highly interesting additional perspectives on how variations in preferred structures emerge.…”

Section: Lj and Morse Clustersmentioning

confidence: 99%

Pure and Hybrid Evolutionary Computing in Global Optimization of Chemical Structures: from Atoms and Molecules to Clusters and Crystals

Sarkar,

Bhattacharyya

2015

Preprint

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The growth of evolutionary computing (EC) methods in the exploration of complex potential energy landscapes of atomic and molecular clusters, as well as crystals over the last decade or so is reviewed. The trend of growth indicates that pure as well as hybrid evolutionary computing techniques in conjunction of DFT has been emerging as a powerful tool, although work on molecular clusters has been rather limited so far. Some attempts to solve the atomic/molecular Schrodinger Equation (SE) directly by genetic algorithms (GA) are available in literature. At the Born-Oppenheimer level of approximation GA-density methods appear to be a viable tool which could be more extensively explored in the coming years, specially in the context of designing molecules and materials with targeted properties.

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A detailed investigation on the global minimum structures of mixed rare‐gas clusters: Geometry, energetics, and site occupancy

Cited by 17 publications

References 51 publications

Low‐energy structures of benzene clusters with a novel accurate potential surface

Low‐energy structures of benzene clusters with a novel accurate potential surface

New insights on lithium-cation microsolvation by solvents forming hydrogen-bonds: Water versus methanol

Pure and Hybrid Evolutionary Computing in Global Optimization of Chemical Structures: from Atoms and Molecules to Clusters and Crystals

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