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Typical HF type calculations

It is strongly recommended to perform standard DFT calculations first, and to start HF type calculations from a preconverged WAVECAR file.

A typical INCAR file for a HF or hybrid HF/DFT calculation for an insulator or semiconductor has the following input lines:


 ISTART = 1
 LHFCALC = .TRUE. ; HFSCREEN = 0.2
 NBANDS = number of occupied bands
 ALGO = All ; TIME = 0.4
 ENCUTFOCK = 0  ! omit flag for high quality calculations
 NKRED     = 2  ! omit flag for high quality calculations
For metals and small gap semiconductors it is recommended to use.

 ISTART = 1
 LHFCALC = .TRUE. ; HFSCREEN = 0.2
 ALGO = Damped ; TIME = 0.4
 ENCUTFOCK = 0  ! omit flag for high quality calculations
 NKRED     = 2  ! omit flag for high quality calculations
These input files select the HSE06 functional, which tends to yield very similar thermochemistry as the PBE0 functional, but converges more rapidly with respect to the number of k-points [68]. We thus recommend to apply and use this functional instead of the more demanding PBE0 functional. The NKRED flag is applicable, if and only if the number of k-points is dividable by 2 (see Sec. 6.63.7). ENCUTFOCK selects a small FFT grid for the fast-Fourier-transforms (see Sec. 6.63.4). For high accuracy NKRED and in particular ENCUTFOCK might be ommited, but we recommend to do this only after preconverging the wavefunctions and atomic positions with these flags specified.

Mind, that the parameter TIME defaults to 0.4, and for the present algorithm this hardly ever needs to be changed. If divergence is observed, simply decrease TIME until the damped or conjugate gradient algorithm becomes stable (see Sec. 6.43 and 6.47).


next up previous contents
Next: Optical properties and density Up: HF type calculations Previous: NKRED, NKREDX, NKREDY, NKREDZ   Contents
Georg Kresse
2007-03-01