**Importance of scf.fixed.grid in phonon calculations** |
- Date: 2023/05/30 12:17
- Name:
**Masanobu Miyata**
<m-miyata@jaist.ac.jp>
- Dear Ozaki-sensei,
When running a phonon calculation, should I explicitly state "scf.fixed.grid 0 0 0" for all displacement pattern input files in the process of calculating total energy for multiple displacement patterns? Referring to the OpenMX manual, it explains: "The total energy depends on the atomic coordinates and the relative position between the grids. When calculating interaction energies or energy curves as a function of atomic coordinates, it is important to maintain this relative position in all calculations required for those series of calculations, because it is important to reduce errors". It seems more accurate to align the Grid Origin by explicitly stating "scf.fixed.grid 0 0 0" in all files. For simple systems such as Si, no difference occurred, but for systems where weak interactions are important, the phonon bands changed slightly.
Best regards, Miyata
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