Small atomic clusters: quantum chemical research of isomeric composition and physical properties

In this review, we give a brief summary of methodological and computational aspects of determination of structure and different size-dependent properties of small atomic clusters by means of computational quantum chemistry. Particular attention is paid to the accurate calculation of thermodynamic properties of clusters with allowance for the vibrational anharmonicity and contribution of excited electronic states. We describe in detail the problems and consequences related to accounting for the contribution of isomeric forms to the observable physical and thermodynamic characteristics. The physical size-dependent properties discussed in this review are the binding energy, zero-point energy, collision diameter, polarizabilities, ionization potential, electron affinity, specific heat capacity, and reduced Gibbs energy. The major part of the review deals with the methodology for physically sound extrapolating the multitude of size-dependent physical and thermodynamic properties of small clusters toward significantly larger (nanometer- and micrometer-sized) particles.