Problem in relaxing cell dimensions when using hybrid functi

questions related to VASP with GPU support (vasp.5.4.1, version released in Feb 2016)

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Problem in relaxing cell dimensions when using hybrid functi

#1 Post by jcconesa » Thu Oct 24, 2019 1:10 pm

I have found that when using GPUs for relaxing cell dimensions (ISIF=3) in calculations of paramagnetic lanthanide oxides involving a hybrid functional (e.g. HSE06) the results are weird: the cell volume increases by a factor of 3 or more, and the energy computed (probably correctly) in the first cycle rockets to much higher values in subsequent relaxation circles.
Has someone found a similar thing? I am using VASP 5.4.4, compiled with intel_parallel_studio_xe_2017, impi-2017.2.174 and cuda/9.2. The problem appears with both K80 and P100 GPUs. I am using these flags in INCAR:

ALGO=All; TIME=0.1 (Algo=Damped behaves similarly, and other TIME values make no change)
ISYM=0; LREAL=.TRUE.; LSCAAWARE = .FALSE. (other values except LREAL=.FALSE. behave similarly)
PREC = Accurate; ENCUT=550; EDIFF=1E-5
IBRION = 2 (values of 1 and 3, with any POTIM, behave similarly)
NELM values are high, and MAGMOM values ensure that initial spin symmetry is broken.

The problem appears only, as I said, when GPUs, a hybrid functional and cell dimensions relaxation all occur simultaneously.
If this were a real bug in VASP it would be good to correct it before the new VASP 6 version were released.
José C. Conesa
Institute of Catalysis, CSIC, Madrid

Posts: 12
Joined: Tue Nov 12, 2019 7:00 pm

Re: Problem in relaxing cell dimensions when using hybrid functi

#2 Post by guiyang_huang1 » Wed Nov 13, 2019 3:11 pm

I also observed this problem.

It only happened for hybrid DFT and ISIF=3.

Using ISIF=4, and changing the lattice constant does not have problem.

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