ML_OUTBLOCK
ML_OUTBLOCK = [integer]
Default: ML_OUTBLOCK = 1
Description: Output distance in number of steps for molecular-dynamics simulations with machine-learned force fields in prediction-only mode (ML_MODE = run).
| Important: This tag is only available as of VASP.6.4.0. Unfortunately, the implementation of this feature was incomplete before VASP.6.4.3. In VASP versions prior to 6.4.3 there was still substantial remaining per-time-step output, in particular in vasprun.xml and vaspout.h5 (see table below). If possible, please use VASP.6.4.3 or higher for production runs with potentially large file output. |
By default VASP writes all results at every molecular-dynamics step (ML_OUTBLOCK = 1). However, this may become inefficient when running long trajectories in production runs with a machine-learned force field in prediction-only mode (ML_MODE = run). This is particularly true if the force field supports the fast execution mode, i.e., refitting was performed with ML_MODE = refit. Then, depending on the system size, writing output each time step may hinder performance, cause heavy I/O load and create unnecessary large files. In order to circumvent these problems ML_OUTBLOCK = n instructs VASP to write screen and file output only every n time steps.
In order to further increase the efficiency, calculation and output of pair-correlation functions can be completely switched off by setting ML_OUTPUT_MODE = 0.
| Warning: This tag will potentially override defaults and INCAR values of NBLOCK! NBLOCK will be automatically set to the maximum of ML_OUTBLOCK and NBLOCK. |
A comparison of the effects of NBLOCK and ML_OUTBLOCK on the output frequency of different files/properties is given in the following table. Here, "yes" means the output will only be written in the interval in time steps given by the tag value. On the other hand, "no" indicates that the output will be written every time step regardless of the tag value.
| Output file/property | NBLOCK | ML_OUTBLOCK | |
|---|---|---|---|
| ≤ 6.4.2 | ≥ 6.4.3 | ||
| screen output | no | yes | yes |
| OSZICAR | no | yes | yes |
| OUTCAR | |||
| ↳ energies and time | no | no | yes |
| ↳ forces and stress | yes | yes | yes |
| CONTCAR | no | yes | yes |
| XDATCAR | yes | yes | yes |
| PCDAT (1) | yes | yes | yes |
| REPORT | yes | yes | yes |
| ML_LOGFILE | no | yes | yes |
| ML_HEAT | no | no | yes |
| ML_EATOM | no | no | yes |
| vasprun.xml | |||
| ↳ energy | no | no | yes |
| ↳ forces (1) | no | no | yes |
| ↳ stress (1) | no | no | yes |
| ↳ structure (1) | no | no | yes |
| ↳ time | no | no | yes |
| vaspout.h5 | |||
| ↳ energies | no | no(2) | yes |
| ↳ forces | no | no(2) | yes |
| ↳ stress | no | no(2) | yes |
| ↳ position_ions | yes | yes | yes |
| ↳ lattice_vectors | yes | yes | yes |
| ↳ ion_velocities | yes | yes | yes |
| ↳ pair_correlation (1) | yes | yes | yes |
(1) ML_OUTPUT_MODE = 0 can disable output completely
(2) Zeros are written for intermediate steps
Related tags and articles
ML_LMLFF, ML_MODE, ML_LFAST, ML_IERR, ML_OUTPUT_MODE, NBLOCK