Eur. Phys. J. D (2015) 69: 211
https://doi.org/10.1140/epjd/e2015-60308-0

Regular Article

Quantum chemical study of small B_nC_m cluster structures and their physical properties^*

Central Institute of Aviation Motors, Aviamotornaya 2, 111116 Moscow, Russia

^a e-mail: star@ciam.ru

Received: 26 May 2015
Received in final form: 8 July 2015
Published online: 15 September 2015

Abstract

Different isomeric forms of B_nC_m clusters with n = 0, ..., 5, m = 0, ..., 5 with the isomerization energy up to 5 eV have been identified by using the multi-step heuristic algorithm based on semiempirical, ab initio and density functional theory calculations. Physical properties, such as rotational constants and characteristic vibrational temperatures, collision diameter, enthalpy of formation, cohesive energy, dipole moment, static isotropic polarizability and magnetic moment of different isomeric forms have been obtained with the usage of density functional theory. It has been revealed that the electric properties of clusters depend on their structure. It was found that the isomers with linear structure contribute mostly to the average polarizability of the ensemble of the isomeric forms of given class of clusters. Temperature-dependent thermodynamic properties of clusters including specific heat capacity and entropy were calculated taking into account the contribution of excited electronic states and possible isomeric forms in the anharmonic oscillator approximation for vibrational degrees of freedom. It was shown that the effect of structural isomers on the thermodynamic properties of the Boltzmann ensemble of clusters can be significant.