First-Principles Study of the Electronic Structure, Optical Properties, and Lattice Dynamics of BC2N

摘要

First-principles calculations of the electronic, optical, and lattice dynamic properties of c-BC2N, w-BC2N, cp-BC2N, z-BC2N, and t-BC2N were performed with the density functional theory (DFT) plane-wave pseudopotential method. It is found that the difference in electronic structures and optical properties is arising from the different numbers and species of chemical bonds in the five phases. The vibration analysis shows three main frequency regions arising from different relative movements among the B, C, and N atoms for the five phases. The calculation demonstrates that Z-BC2N and t-BC2N have more vibration states and own much higher vibration frequencies. The experimental Raman peak, well reproduced in z-BC2N and t-BC2N, has been assigned to be the serious relative translational movements of C atoms (C1 and C3 for z-BC2N; C2 and C3 for t-BC2N) along the z direction with the other atoms moving slightly. Though the five phases may not display excellent heat capacities in room temperature (about 30 J/mol/K), the high Debye temperatures, reaching about 1700 K, may lead to some research and application interests in the thermodynamic aspect.