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Next: 1.3 VASP 4.2 Up: 1 New features added Previous: 1.1 VASP 3.1

1.2 VASP 3.2

A new utility for creating the param.inc file automatically was added. The name of the utility is

> makeparam
and it prompts a param.inc file to the screen. (Goto the  /src/vasp.../ directory and type make makeparam to compile this small utility). Before running the makeparam utility all other input files (INCAR, POSCAR, POTCAR, EXHCAR and KPOINTS) must exist in the current work directory. In the INCAR file a new tag was added to support the automatic generation of the param.inc file. This tag is named PREC, and determines the accuracy of the calculation. Possible settings for PREC are

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Default is Medium. For PREC=High wrap around errors are avoided. For PREC= Low or Medium the 3/4 rule is used (see section 10.4), i.e. NGX,Y,Z is set to 3/4 of the value, which avoids wrap around errors. This flag also determines ENCUT if no value is given in the INCAR file. For PREC=Low, ENCUT will be set to the maximal ENMIN value found on the POTCAR files, for PREC=Medium or High ENCUT will be set to maximal ENMAX value on the POTCAR file (section 5.4 and 7.7).

Another tag was added to perform GGA calculation with pseudopotentials generated with conventional LDA reference configurations. The tag is named GGA. Possible options are

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(See section 7.35).

It now no longer necessary to have an EXHCAR file in the work directory. If no EXHCAR file is found by VASP a default table will be generated. This table is very accurate and the range of the table should be sufficient for most calculations (see section 5.9 for default values).

A small section was added in the manual (see section 7.15) which explains for several cases how the INCAR file might be set up. Please read this section carefully.

A tutorial section was added. This should help you to make your first steps with VASP (see section 2.2).

For the ionic relaxation the tag EDIFFG has now an additional meaning: if the value is negative the relaxation will stop if all forces are smaller than the tex2html_wrap_inline4359 EDIFFG tex2html_wrap_inline4359 (see section 7.16).

We now strongly recommend the use of the Verlet algorithm instead of the predictor corrector algorithm for ab initio MD's. The energy stability is usually better (especially if the time step is large in comparison to the typical frequencies) for the Verlet algorithm than for the predictor corrector scheme previously used by VASP.

The meaning of the tag LREAL has been extended recently. Now it is possible to set

  LREAL = On
Only the first character is important (and only the characters 'o' and 'O' are allowed). This flag supersedes
  LREAL = .TRUE.
and should be used from now on. For compatibility reasons you can still write LREAL = .TRUE.; in this case the default real space operators (as written to the POTCAR file are used). Because the default real space projectors are only optimized for the default cutoff, they are not very accurate and efficient for systems containing more than one species. The new tag LREAL = O re-optimizes the real space projectors on the fly (i.e. on startup of VASP). For further details we refer to section 7.34.

The section 10 has been rewritten, please read it once again. Also check the description of the makeparam utility once again (Sec. 6.1).


next up previous contents
Next: 1.3 VASP 4.2 Up: 1 New features added Previous: 1.1 VASP 3.1

MASTER USER VASP
Mon Mar 29 10:38:29 MEST 1999