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Efficient relaxation from an unreasonable starting guess

If you want to do an efficient relaxation from a configuration that is not close to the minimum, set the following values in the INCAR file (for briefness the recommended setup is lacking, see Sec. 6.2.3):

NELMIN = 5           #  do a minimum of four electronic steps
EDIFF  = 1E-2        #  low accuracy
EDIFFG = -0.3        #  accuracy of ions not too high
NSW    = 10          #  10 ionic steps in ions
IBRION =  2          #  use CG algorithm
This way only low accuracy will be required in the first few steps, but since a minimum of 5 electronic steps is done the accuracy of the calculated electronic groundstate will gradually improve. If you are a slightly advanced user you can also use the damped MD algorithm, which is usually more efficient than the CG one:
IBRION =  1 ; SMASS = 0.4  # damped MD  
POTIM  = 0.4         # time step needs to chosen with care
In this case, a too large POTIM will result in divergence.



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