First Principle Calculations of Pressure Induced Structural and Electronic Properties in Americium Monochalcogenides

The tight-binding linear muffin-tin orbital (TB-LMTO) with in the local density approximation is used to calculate total energy, lattice parameters, bulk modulus, density of states and energy band structures of americium monochalcogenides at ambient as well as high pressure. It is found that AmX (X=S, Se, Te) compounds are stable in NaCl - type structure under ambient pressure. We predict a structural phase transition from NaCl-type (B-1-phase) structure to CsCl-type (B-2-phase) structure for these compounds in the pressure range of 26.0 - 15.0 GPa (AmS to AmTe). From energy band diagram it is observed that AmX compounds exhibit metallic behaviour. The calculated ground state properties such as lattice parameters and bulk modulus are in general good agreement with available experimental and theoretical data.