title: Planar vs. three-dimensional X6(2-), X2Y4(2-), and X3Y3(2-) (X, Y = B, Al, Ga) metal clusters: an analysis of their relative energies through the turn-upside-down approach.
abstract: Despite the fact that B and Al belong to the same group 13 elements, the B6(2-) cluster prefers the planar D2h geometry, whereas Al6(2-) favours the Oh structure. In this work, we analyse the origin of the relative stability of D2h and Oh forms in these clusters by means of energy decomposition analysis based on the turn-upside-down approach. Our results show that what causes the different trends observed is the orbital interaction term, which combined with the electrostatic component do (Al6(2-) and Ga6(2-)) or do not (B6(2-)) compensate the higher Pauli repulsion of the Oh form. Analysing the orbital interaction term in more detail, we find that the preference of B6(2-) for the planar D2h form has to be attributed to two particular molecular orbital interactions. Our results are in line with a dominant delocalisation force in Al clusters and the preference for more localised bonding in B metal clusters. For mixed clusters, we have found that those with more than two B atoms prefer the planar structure for the same reasons as for B6(2-).
authors.affiliation: Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain. miquel.sola@udg.edu.
authors.forename: Ouissam
authors.initials: O
authors.lastname: El Bakouri
authors.affiliation: Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain. miquel.sola@udg.edu.
authors.forename: Miquel
authors.initials: M
authors.lastname: Solà
authors.affiliation: Departament de Química Inorgànica i Orgànica & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain. jordi.poater@gmail.com and Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam, De Boeleaan 1083, NL-1081HV Amsterdam, The Netherlands and Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Poater