Insights on the Realgar Crystal Under Pressure from XP-PCM and Periodic Model Calculations

The spectroscopic properties of As₄S₄ with pressure have been computed by the quantum mechanical XP-PCM method and by density functional theory periodic calculations. The comparison has allowed the interpretation of the available experimental data. By comparison of the two methods and with experiments, we show that the XP-PCM method is able to reproduce the same behaviour of the periodic calculations with much lower computational cost allowing to be adopted as a first choice computational tool or a qualitative interpretation of molecular crystals properties under pressure.