Ground-state structure ofβ−C3N4by first-principles calculations

Abstract

The ground-state structure of $\ensuremath{\beta}\ensuremath{-}{\mathrm{C}}_{3}{\mathrm{N}}_{4}$ has been examined systematically by the first-principles molecular-dynamics (FPMD) method combined with a variable unit-cell shape algorithm based on the Parrinello-Rahman method. For each configuration with the possible symmetry of ${P6}_{3}/m,$ ${P6}_{3},$ and $P3,$ we optimized both atomic coordinates and unit cell shapes at the same time. We observed that the results of each symmetry converged to almost the same atomic structure. We conclude that the ground-state structure of $\ensuremath{\beta}\ensuremath{-}{\mathrm{C}}_{3}{\mathrm{N}}_{4}$ has ${P6}_{3}/m$ symmetry.