How to restart relaxation of cell shape/volume?; ISTART = 2; "Coefficients changed" error

[kevin.driver]

Dear VASP community,

According to the manual, http://cms.mpi.univie.ac.at/vasp/vasp/node99.html,
"all volume/cell shape relaxation algorithms implemented in VASP work with a constant basis set, so continuing such jobs requires to set ISTART=2 to get a 'consistent restart' with respect to the previous runs...." "The set of plane waves will not be changed even if the cut-off energy or the cell size/shape given on files INCAR and POSCAR are different from the values stored on the file WAVECAR."

In a test relaxation calculation, I stop the calculation after the first ionic step and write out the WAVECAR file. I then copy the CONTCAR to POSCAR and attempt to restart the relaxation with ISTART=2 as follows:

SYSTEM = Silica
PREC = Accurate
ENCUT = 900
ISIF = 4
IBRION = 2
ISMEAR = -5
ISPIN = 1
EDIFF = 0.1E-08
NSW = 1
NELM = 9
ISTART = 2

LWAVE = .TRUE.
LCHARG = .TRUE.

However, the calculation quickly dies with the "coefficients changed" error:
ERROR: while reading WAVECAR, plane wave coefficients changed 6909 6909

I thought ISTART=2 was supposed to force the restart calculation to use the planewave basis that is stored in the WAVECAR file. Anyone have an idea of what is causing this issue?

Thank you,
Kevin Driver

[boris]

Hi
To restart from the WAVECAR file, I use ISTART=1 and ICHARG=0.

To restart from the CHGCAR file, I use ISTART=0 and ICHARG=1.

You should try these.

Best regards.

B.