Polymorphism and thermodynamic ground state of silver fulminate studied from van der Waals density functional calculations

摘要: Silver fulminate (AgCNO) is a primary explosive, which exists in two polymorphic phases, namely, orthorhombic (Cmcm) and trigonal (R3) forms at ambient conditions. In the present study, we have investigated effect of pressure temperature on relative phase stability polymorphs using planewave pseudopotential approaches based Density Functional Theory (DFT). van der Waals interactions play significant role predicting they can be effectively captured by semi-empirical dispersion correction methods contrast to standard DFT functionals. Based our total energy calculations DFT-D2 method, Cmcm structure found preferred thermodynamic equilibrium under studied range. Hitherto R3 phases denoted as α- β-forms AgCNO, respectively. Also induced transition seen functionals same was not observed with method. The equation state compressibility both were investigated. Electronic optical properties calculated full potential linearized augmented plane wave method within Tran-Blaha modified Becke-Johnson potential. electronic shows that α, β are indirect bandgap insulators values 3.51 4.43 eV, nature chemical bonding analyzed through charge density plots partial states. Optical anisotropy, electric-dipole transitions, photo sensitivity light from spectra. Overall, study provides an early indication experimentalists avoid formation unstable β-form AgCNO.