CHECKPOINT FD: Difference between revisions
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{{TAGDEF|CHECKPOINT_FD|[string]}} | {{TAGDEF|CHECKPOINT_FD|[string]}} | ||
Description: | Description: Enables a finite differences calculation to be restarted or split up into displacements. | ||
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{{Available|6.6.0}} | {{Available|6.6.0}} | ||
{{NB|important|This feature requires [[:Category:HDF5_support | HDF5 support]].}} | {{NB|important|This feature requires [[:Category:HDF5_support | HDF5 support]].}} | ||
{{NB|mind|This is currently only available for {{TAG|IBRION|6}}.}} | {{NB|mind|This is currently only available for {{TAG|IBRION|6}}.}} | ||
Phonon (or vibrational) modes can be calculated using [[Phonons from finite differences | 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 {{TAG|CHECKPOINT_FD}} (with {{TAG|IBRION|6}}), it is possible to [[Construction:Restarting_finite_differences_calculations#Restarting_a_finite_difference_calculation | restart a calculation that crashed]] from the last displacement, or [[Construction:Restarting_finite_differences_calculations#Splitting_a_finite_difference_calculation | split the calculation into individual displacements]]. The displacements are written to the {{FILE|vaspcheckfd.h5}} file. | Phonon (or vibrational) modes can be calculated using [[Phonons from finite differences | 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 {{TAG|CHECKPOINT_FD}} (with {{TAG|IBRION|6}}), it is possible to [[Construction:Restarting_finite_differences_calculations#Restarting_a_finite_difference_calculation | restart a calculation that crashed]] from the last displacement, or [[Construction:Restarting_finite_differences_calculations#Splitting_a_finite_difference_calculation | split the calculation into individual displacements]]. The displacements are written to the {{FILE|vaspcheckfd.h5}} file. | ||
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==Related tags and articles== | ==Related tags and articles== | ||
[[ | [[Phonons from finite differences]], [[Restarting finite differences calculations]], {{TAG|IBRION}}, {{FILE|vaspcheckfd.h5}}, {{FILE|CONTCAR_disp-N}} | ||
{{sc| | {{sc|CHECKPOINT_FD|HowTo|Workflows that use this tag}} | ||
[[Category:INCAR tag]][[Category:Phonons | [[Category:INCAR tag]][[Category:Phonons]] | ||
Revision as of 13:54, 11 March 2026
CHECKPOINT_FD = [string]
Description: 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