First-principles study of the structural, optical and thermal properties of AgGaSe2

We have calculated the structural, optical and thermal properties of an AgGaSe2 crystal using ultrasoft pseudopotentials and the generalized gradient approximation ( GGA). The calculated results are in good agreement with the available experimental data and theoretical values. The optical property calculations are performed for the energy range 0-22.5 eV. The thermal properties of the AgGaSe2 are calculated using the quasi-harmonic Debye model. The pressure and temperature dependences of the bulk modulus, the heat capacity, the Gruneisen parameter, the Debye temperature and the thermal expansion coefficient, as well as the entropy, are obtained in the ranges of 0-6 GPa and 0-1200 K. We also found in our present work that the effects of pressure and temperature on different thermal properties are significant and very useful for crystal growth.