Account of surface contribution to thermodynamic properties of lead selenide films

Abstract

Being based on the density functional theory (DFT), computer simulation of the surface effect on thermodynamic parameters of lead selenide (PbSe) has been performed in this work. Applying the thermodynamic approach, the choice of model for the plane PbSe [200] preferred orientations has been justified, which indicates domination of the energy of surface states, while minimization of interface energy and deformation are less important in overall changing the free energy. The thermodynamic parameters for the surface of crystals and their temperature dependences in the framework of DFT method and using the hybrid functional B3LYP have been calculated, namely: energy ∆E, enthalpy ∆H, Gibbs’ free energy ∆G, isobaric heat capacities CP and isovolume heat capacities CV, entropy ∆S. The analytical expressions of temperature dependences for these thermodynamic parameters approximated using quantum-chemical calculation data have been obtained. The analysis of temperature dependences for the heat capacity corresponds to the experimental data and the Djulong–Pti law.