| UHTCs | ultra high-temperature ceramics |
| DFT | density functional theory |
| DFPT | density functional perturbation theory |
| PAW | projector augmented-wave |
| PP-PW | pseudopotential, plane-wave |
| XC | exchange-correlation |
| LDA | local density approximation |
| GGA | generalized gradient approximation |
| PBE | Perdew-Burke-Ernzerhof |