The electronic, optical, and vibrational properties of Ag3X (X = S, Se) with density functional theory

Using ab initio first-principles calculations, we investigate the structural, electronic, optical, and vibrational properties of Silver Sulphide Ag3S and Selenide Ag3Se with nonlocal hybrids exchange-correlation functional. With our computational predictions, we manage to classify the material to be Fermi-Dirac semi-metal, rather than Weyl metal. Our calculated results show that the electronic band in between the Fermi-Dirac cone shifts downward when we replace the element Sulphide S with Selenide Se. The obtained optical results such as absorption coefficients and dielectric functions (conductivity, reflectivity, etc.) are similar for both Ag3S and Ag3Se. A high absorption coefficient of 2 x 105 cm(-1) has been reported, and about 50% of light is reflected. In Raman spectra, the A(g)(X-X) managed to shift downward when replacing the element X, sulphide S with selenide Se, while the A(g)(rigid) shifts upward (to higher wavelength). The rotation and vibration of the bonding between atoms have also been explained. The calculated results of Silver-VI compounds provide useful information in the exploitation of more complicated structures.

Automated summary

Using ab initio first-principles calculations, this study investigates the properties of Ag3S and Ag3Se with nonlocal hybrids exchange-correlation functional. The material is classified as Fermi-Dirac semi-metal. When replacing S with Se, the electronic band shifts downward. The optical results, such as absorption coefficients and dielectric functions, are similar for both compounds.