CHECKPOINT FD: Difference between revisions

Latest revision as of 14:12, 11 March 2026

CHECKPOINT_FD = CONTINUE | RESET | NONE | SINGLE
Default: CHECKPOINT_FD = RESET

Description: Enables a finite differences calculation to be restarted or split up into displacements.

Phonons 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.

Mind: Available as of VASP 6.6.0

Important: This feature requires HDF5 support.

Mind: This is currently only available for IBRION = 6.

`CHECKPOINT_FD = CONTINUE`

The vaspcheckfd.h5 file is read (if it exists) and the calculation continues where it left off. If the vaspcheckfd.h5 file is missing, a 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 = CONTINUE will 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`

No vaspcheckfd.h5 file is written. This is the behavior of the code before VASP 6.6.0.

`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. The calculation stops after performing one electronic minimization to obtain the SCF solution of the unperturbed structure.

To run the calculation for a specific displacement, create a directory disp-N, copy across the corresponding CONTCAR_disp-N file 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.

@@ Line 1: / Line 1: @@
 {{DISPLAYTITLE:CHECKPOINT_FD}}
-{{TAGDEF|CHECKPOINT_FD|[string]}}
+{{TAGDEF|CHECKPOINT_FD| CONTINUE {{!}} RESET {{!}} NONE {{!}} SINGLE | RESET}}
 Description: Enables a finite differences calculation to be restarted or split up into displacements.
 ----
+[[Phonons]] 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.
 {{Available|6.6.0}}
 {{NB|important|This feature requires [[:Category:HDF5_support | HDF5 support]].}}
 {{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.
 === {{TAG|CHECKPOINT_FD|CONTINUE}} ===
-*{{FILE|vaspcheckfd.h5}} file is read (if it exists) and the calculation continues where it left off.
+:The {{FILE|vaspcheckfd.h5}} file is read (if it exists) and the calculation continues where it left off. If the {{FILE|vaspcheckfd.h5}} file is missing, a {{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}}.
-*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}}.
+: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.
-*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.
 === {{TAG|CHECKPOINT_FD|RESET}} (default) ===
 :Overwrite the {{FILE|vaspcheckfd.h5}} file and start from scratch. The rest is identical to {{TAG|CHECKPOINT_FD|CONTINUE}}.
 === {{TAG|CHECKPOINT_FD|NONE}} ===
-:Behavior of the code before VASP 6.6.0. No {{FILE|vaspcheckfd.h5}} file is written.
+:No {{FILE|vaspcheckfd.h5}} file is written. This is the behavior of the code before VASP 6.6.0.
 === {{TAG|CHECKPOINT_FD|PREPARE}} ===
-*The {{FILE|vaspcheckfd.h5}} file is created (or overwritten) and filled with metadata.
+:The {{FILE|vaspcheckfd.h5}} file is created (or overwritten) and filled with metadata. For each displacement, a {{FILE|CONTCAR_disp-N}} file is written containing the Nth displacement. The calculation stops after performing one [[electronic minimization]] to obtain the SCF solution of the unperturbed structure.
-*For each displacement, a {{FILE|CONTCAR_disp-N}} file is written containing the Nth displacement. VASP then stops after one SCF.
+:To run the calculation for a specific displacement, create a directory <code>disp-N</code>, copy across the corresponding {{FILE|CONTCAR_disp-N}} file and rename it to {{FILE|POSCAR}}. Then, run the calculation with {{TAG|CHECKPOINT_FD|SINGLE}}.
-*To run this displaced calculation, create a directory ''disp-N'', copy across the corresponding {{FILE|CONTCAR_disp-N}} file into it and rename it to {{FILE|POSCAR}}. Then run the calculation with {{TAG|CHECKPOINT_FD|SINGLE}}.
 === {{TAG|CHECKPOINT_FD|SINGLE}} ===
 :This mode is used to run the individual single-shot VASP calculations produced by {{TAG|CHECKPOINT_FD|PREPARE}}. This also produces a {{FILE|vaspcheckfd.h5}} file in the corresponding directory that contains the displaced data.

Latest revision as of 14:12, 11 March 2026

CHECKPOINT_FD = CONTINUE

CHECKPOINT_FD = RESET (default)

CHECKPOINT_FD = NONE

CHECKPOINT_FD = PREPARE

CHECKPOINT_FD = SINGLE

Related tags and articles

`CHECKPOINT_FD = CONTINUE`

`CHECKPOINT_FD = RESET` (default)

`CHECKPOINT_FD = NONE`

`CHECKPOINT_FD = PREPARE`

`CHECKPOINT_FD = SINGLE`