Vibrational Properties and the Lattice Specific Heat of an Alternating Iron Chain Structure Compound CsFeS2

The alternating chain-structure compound of CsFeS2 consists of [FeS2]n chains characterized with two different within chains inter-atom distances of average value of 2.7 Å. That feature sets the CsFeS2 compound apart from the family of similar compounds like AFeCh2 (A—K, Rb; Ch—S, Se) which show all intra-chain Fe–Fe distances are identical within a compound. The one of well elucidating property of a solid’s magnetic system is a temperature dependence of its specific heat. It allows estimating the interaction pattern in different regimes and to distinguish the types of magnetic phase transitions. So, the comparative studies of all the mentioned compounds might further shed a light on the complex magnetic properties of all that compounds. So, in the present study, the phonon densities of states were calculated within direct approach of quasi-harmonic approximation. We used phonon density of states to calculate lattice contribution to the specific heat. The results of the present paper could be used in further analysis of thermodynamic, optical and magnetic properties of CsFeS2 compound.