CHECKPOINT FD: Difference between revisions
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{{DISPLAYTITLE:CHECKPOINT_FD}} | {{DISPLAYTITLE:CHECKPOINT_FD}} | ||
{{TAGDEF|CHECKPOINT_FD|[string]}} | {{TAGDEF|CHECKPOINT_FD|[string]}} | ||
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;{{TAG|CHECKPOINT_FD|CONTINUE}} | ;{{TAG|CHECKPOINT_FD|CONTINUE}} | ||
*{{FILE|vaspcheckfd.h5}} file is read (if it exists) and the calculation continues where it left off. | *{{FILE|vaspcheckfd.h5}} file is read (if it exists) and the calculation continues where it left off. | ||
*Otherwise, {{FILE| | *Otherwise, {{FILE|vaspcheckfd.h5}} is created and the displacements are written to it. In both cases, the calculation will finish with the complete {{FILE|vaspcheckfd.h5}}. | ||
*Repeating {{TAG|CHECKPOINT_FD|CONTINUE}} will perform a single SCF at the equilibrium structure and read the displacements from {{FILE|vaspcheckfd.h5}}. | *Repeating {{TAG|CHECKPOINT_FD|CONTINUE}} will perform a single SCF at the equilibrium structure and read the displacements from {{FILE|vaspcheckfd.h5}}. | ||
*This mode also detects if the calculation is a single VASP calculation or if it was split into separate pieces. If it has been split, all the calculations need to have finished, or an error will be produced. | *This mode also detects if the calculation is a single VASP calculation or if it was split into separate pieces. If it has been split, all the calculations need to have finished, or an error will be produced. | ||
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{{sc|NSW|Examples|Examples that use this tag}} | {{sc|NSW|Examples|Examples that use this tag}} | ||
[[Category:INCAR tag]][[Category:Phonons]][[Category:Electron-phonon interactions]] | |||
Latest revision as of 15:07, 4 March 2026
CHECKPOINT_FD = [string]
Description: CHECKPOINT_FD enables a finite differences calculation to be restarted or split up into displacements
| Mind: Available as of VASP 6.6.0 |
| Important: This feature requires HDF5 support. |
Mind: This is currently only available for IBRION = 6.
|
Phonon (or vibrational) modes can be calculated using finite differences. A series of displacements is made, DFT calculations are performed on each of these, and then the second-order force constants are computed and the dynamical matrix constructed, from which the phonon modes and frequencies are calculated. Using CHECKPOINT_FD (with IBRION = 6), it is possible to restart a calculation that crashed from the last displacement, or split the calculation into individual displacements. The displacements are written to the vaspcheckfd.h5 file.
CHECKPOINT_FD = CONTINUE
- vaspcheckfd.h5 file is read (if it exists) and the calculation continues where it left off.
- Otherwise, vaspcheckfd.h5 is created and the displacements are written to it. In both cases, the calculation will finish with the complete vaspcheckfd.h5.
- Repeating
CHECKPOINT_FD = CONTINUEwill perform a single SCF at the equilibrium structure and read the displacements from vaspcheckfd.h5. - This mode also detects if the calculation is a single VASP calculation or if it was split into separate pieces. If it has been split, all the calculations need to have finished, or an error will be produced.
CHECKPOINT_FD = RESET- (default)- Overwrite the vaspcheckfd.h5 file and start from scratch. The rest is identical to
CHECKPOINT_FD = CONTINUE. CHECKPOINT_FD = NONE- Behavior of the code before VASP 6.6.0. No vaspcheckfd.h5 file is written.
CHECKPOINT_FD = PREPARE
- The vaspcheckfd.h5 file is created (or overwritten) and filled with metadata.
- For each displacement, a CONTCAR_disp-N file is written containing the Nth displacement. VASP then stops after one SCF.
- To run this displaced calculation, create a directory disp-N, copy across the corresponding CONTCAR_disp-N file into it and rename it to POSCAR. Then run the calculation with
CHECKPOINT_FD = SINGLE.
CHECKPOINT_FD = SINGLE- This mode is used to run the individual single-shot VASP calculations produced by
CHECKPOINT_FD = PREPARE. This also produces a vaspcheckfd.h5 file in the corresponding directory that contains the displaced data.
Related tags and articles
phonons from finite differences, Restarting finite differences calculations, IBRION, vaspcheckfd.h5, CONTCAR_disp-N