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PREC-tag

PREC= Low | Medium | High | Normal | Accurate | Single

Default:    
PREC= Medium for VASP.4.X
= Normal for VASP.5.X


The settings Normal and Accurate are only available in VASP.4.5 and newer versions. The setting Single is only available in VASP.5.1.

Changing the PREC parameter influences the default for four sets of parameters (ENCUT; NGX, NGY, NGZ; NGXF, NGYF, NGZF and ROPT), and it is also possible to obtain the same characteristics by changing the corresponding parameters in the INCAR file (VASP.4.X) directly.

We recommend to use PREC=Normal for calculations in VASP.4.5 and higher (default in VASP.5.X) and PREC=Medium for VASP.4.4.

PREC=Accurate avoids wrap around errors and uses an augmentation grid that is exactly twice as large as the coarse grid for the representation of the pseudo wavefunctions. PREC=Accurate increases the memory requirements somewhat, but it should be used if very accurate forces (phonons and second derivatives) are required. The accuracy of forces can be further improved by specifying ADDGRID = .TRUE. (see Sec. 6.63).

New manual entry for PREC=High:
The use of PREC=High is no longer recommend (and exists only for compatibility reasons). For an accurate stress tensor the energy cutoff should be increased manually, and if additionally very accurate forces are required, PREC=Accurate can be used in combination with an increase energy cutoff. Note, that we now recommend to specify the energy cutoff always manually in the INCAR file, to avoid incompatibilities between calculations (see Sec. 6.2.3).

Old manual entry for PREC=High:
PREC=High, should be used if properties like the stress tensor are evaluated. If PREC=High calculations are too expensive, ENMAX can also be increased manually in the INCAR file, since this is usually sufficient to obtain a reliable stress-tensor.


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Next: ISPIN-tag Up: The INCAR File Previous: ENAUG-tag   Contents   Index
N.B. Requests for support are to be addressed to: vasp.materialphysik@univie.ac.at