INTERACTIVE

INTERACTIVE = [logical]
Default: INTERACTIVE = .FALSE. 

Description: INTERACTIVE enables an interactive mode in which a series of structures is piped into VASP via stdin.

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INTERACTIVE = .TRUE. enables the interactive mode. The interactive mode (IBRION = 11) is executed by inputting a series of structures into the VASP executable, i.e.:

vasp_std < POSCAR.interactive

The number of ionic steps NSW should be set to the number of structures in the POSCAR.interactive file plus one (or any larger value); the number of atoms in these input structures must be constant. Bear in mind that POSCAR.interactive is just a dummy name for a file that pipes the structures to the executable. Each input structure will then be calculated according to the INCAR file and the output will be written as normal.

Important: The corresponding POSCAR file is required. The first set of positions comes from it, and the calculation will not run without it. After the POSCAR structure, the POSCAR.interactive structures will be read.

Fixed lattice (ISIF < 3)

Important: The coordinates of the ions for each structure must be given in fractional/ direct coordinates (Cartesian coordinates are not supported).

For a fixed lattice ISIF < 3, the lattice is defined by the POSCAR file. The input structure (e.g., POSCAR.interactive, or any other name) is as follows:

  0.51602654  0.60200207  0.48355839
  0.47803882  0.52340268  0.50869036
  0.56717477  0.65578242  0.53100206
  0.45116332  0.63676166  0.43537938
  0.31530340  0.74388198  0.64715720
  0.60071504  0.49851047  0.37872126

  0.44216661  0.56361173  0.52960446
  0.36537533  0.54238027  0.56342416
  0.50398907  0.58877046  0.59064245
  0.43618126  0.61788131  0.46024981
  0.45532341  0.84599587  0.53226938
  0.50724841  0.41695239  0.46229896

  0.53802286  0.56353392  0.51036499
  0.47205503  0.63101620  0.50503092
  0.55908887  0.54004979  0.59586980
  0.61484211  0.57816646  0.45750405
  0.42364771  0.83966876  0.53596644
  0.46803897  0.42328326  0.47142822

with the coordinates of the ions for each structure given in fractional/ direct coordinates (Cartesian coordinates are not supported), followed by a blank line, then the next structure, etc. These calculations will then be performed on these structures. As each file is read in, the following will be printed to the stdout:

POSITIONS: reading from stdin

POSITIONS: read from stdin

Variable lattice (ISIF ≥ 3)

When the lattice is not fixed ISIF ≥ 3, the input structure (direct or Cartesian) requires that the lattice also be defined, i.e., POSCAR.interactive is a list of POSCAR files (i.e., the same format as an XDATCAR file):

unknown system
           1
    -5.608199   -5.441585   -0.050512
    -5.462972   -0.042950   -5.505922
     0.000000   -5.460525   -5.460525
   Si
    16
Direct configuration=          29
   0.16107731  0.07535964  0.14569368
   0.08094105  0.11968075  0.63676797
   0.12674262  0.62205394  0.16549329
   ...
   0.76282682  0.79675752  0.20047467
   0.72878930  0.77068250  0.75446889
unknown system
           1
    -5.614679   -5.440682   -0.050669
    -5.464721   -0.042862   -5.507583
     0.000000   -5.461359   -5.461359
   Si
    16
Direct configuration=          30
   0.16122201  0.07550654  0.14846295
   0.08038750  0.12050178  0.63429276
   0.12832567  0.62549860  0.16421982
   ...
   0.76048160  0.79907085  0.19846135
   0.73319285  0.76646271  0.75715487

As each structure is read in, the following will be printed to stdout:

POSITIONS AND LATTICE: reading from stdin

POSITIONS AND LATTICE: read from stdin

Important: Although the lattice changes, the plane-wave basis remains the same. Be sure that your basis is sufficiently converged to avoid Pulay stress.

Tip: We suggest using the interactive mode to systematically improve machine-learned force fields (MLFF) by selecting all structures for which the MLFF shows larger errors, and continue to train the MLFF with those structures. For instance, one can select structures where the maximum spilling factor is significantly larger than the average. Preferably, individual thresholds are set for each species (cf. ML_ESTBLOCK to evaluate the spilling factor).

Related tags and articles

Tags: IBRION, ISIF, NSW

Files: POSCAR, XDATCAR

How-to: Using metadynamics to train a machine-learned force field

Workflows that use this tag