[CP2K-user] EXTERNAL_PRESSURE and PRESSURE_TOLERANCE settings in cell optimisations for crystals
Matt W
mattwa... at gmail.com
Wed Nov 25 14:48:55 UTC 2020
You can find some good quality basis sets in in BASIS_MOLOPT_UCL:
https://github.com/cp2k/cp2k/blob/master/data/BASIS_MOLOPT_UCL
there are also some alternative Lanthanide basis sets available in other
files.
Matt
On Wednesday, November 25, 2020 at 2:44:47 PM UTC sh... at gmail.com wrote:
> Dear Fabian,
> Thanks for the explanation! I've noticed the CELL_REF and OT issues of the
> input file. The CP2K output file also hints about the OT algorithm.
> The reason I use DZV-GTH-PADE basis for Y is that I cannot find GTH-PBE
> basis set for it in the cp2k/data directory. Maybe I should find the
> corresponding basis set in somewhere else.
> Anyway, thanks for your help and suggestions!
>
> Best regards.
> Huaiyang Sun
>
> On Wednesday, November 25, 2020 at 3:26:58 PM UTC+8 fa... at gmail.com
> wrote:
>
>> Dear Huaiyang Sun,
>>
>> Many solids have a bulk modulus in the range of 1 to 100 GPa. A material
>> with a bulk modulus of 10 GPa changes its volume by 1% when subjected to a
>> pressure of 1000 bar. In this case a PRESSURE_TOLERANCE of 100 bar is
>> already accurate to within 0.1% of the volume.
>>
>> The input file has some issues:
>> use CELL_REF for a cell optimization
>> you cannot use OT together with k-points, use DIAGONALIZATION instead
>> I would recomment to not mix different basis sets, especially not using
>> PADE ones for PBE calculations
>>
>> Cheers,
>> Fabian
>> On Wednesday, 25 November 2020 at 04:09:02 UTC+1 sh... at gmail.com wrote:
>>
>>>
>>> Deal all,
>>>
>>> I'm doing a cell optimisation run of a YAG (Y3Al5O12) crystal. I wonder
>>> about the meaning of the tags EXTERNAL_PRESSURE and PRESSURE_TOLERANCE in
>>> the CELL_OPT section of the input. The default values are both 100 bar.
>>> Here are the few points I don't understand,
>>>
>>> 1. If the cell optimisation run is targeted at the input
>>> EXTERNAL_PRESSURE, shouldn't the default PRESSURE_TOLERANCE be given a much
>>> smaller value, like 5.0 or 1.0 bar?
>>>
>>> 2. Why 100 bar? 1 atm = 1.013 bar sounds more reasonable.
>>>
>>> 3. My simple understanding of cell optimisation is to find the minimum
>>> point of the energy-volume (E-V) curve. Then what's the role of external
>>> pressure?
>>>
>>> Here is my input file.
>>>
>>> &GLOBAL
>>> project pristine-opt
>>> run_type CELL_OPT
>>> print_level MEDIUM
>>> &END GLOBAL
>>>
>>> &FORCE_EVAL
>>> METHOD QS
>>>
>>> &SUBSYS
>>> &CELL
>>> ABC 12.0003 12.0003 12.0003
>>> PERIODIC XYZ
>>> MULTIPLE_UNIT_CELL 1 1 1
>>> SYMMETRY CUBIC
>>> &END CELL
>>>
>>> &TOPOLOGY
>>> MULTIPLE_UNIT_CELL 1 1 1
>>> COORD_FILE_FORMAT XYZ
>>> COORD_FILE_NAME yag_from_cif_conven_unit.xyz
>>> &END TOPOLOGY
>>>
>>> &KIND Y
>>> ELEMENT Y
>>> BASIS_SET DZV-GTH-PADE
>>> POTENTIAL GTH-PBE-q11
>>> &END KIND
>>>
>>>
>>> &KIND Al
>>> ELEMENT Al
>>> BASIS_SET DZVP-MOLOPT-SR-GTH
>>> POTENTIAL GTH-PBE-q3
>>> &END KIND
>>>
>>> &KIND O
>>> ELEMENT O
>>> BASIS_SET DZVP-GTH-PBE
>>> POTENTIAL GTH-PBE-q6
>>> &END KIND
>>>
>>> &KIND Ce
>>> ELEMENT Ce
>>> BASIS_SET DZVP-MOLOPT-SR-GTH-q12
>>> POTENTIAL GTH-PBE-q12
>>> &END KIND
>>>
>>> &KIND Yb
>>> ELEMENT Yb
>>> BASIS_SET DZVP-MOLOPT-SR-GTH-q24
>>> POTENTIAL GTH-PBE-q24
>>> &END KIND
>>>
>>> &END SUBSYS
>>>
>>> &DFT
>>> BASIS_SET_FILE_NAME BASIS_SET_YAG
>>> POTENTIAL_FILE_NAME POTENTIAL_YAG
>>>
>>> &MGRID
>>> NGRIDS 4
>>> CUTOFF 600
>>> REL_CUTOFF 60
>>> &END MGRID
>>>
>>> &QS
>>> EPS_DEFAULT 1.0E-12
>>> &END QS
>>>
>>> &POISSON
>>> PERIODIC XYZ
>>> &END POISSON
>>>
>>> &SCF
>>> SCF_GUESS ATOMIC
>>> EPS_SCF 5.0E-7
>>> MAX_SCF 200
>>>
>>> CHOLESKY INVERSE
>>>
>>> &OT ON
>>> MINIMIZER DIIS
>>> &END OT
>>> #&DIAGONALIZATION
>>> # ALGORITHM STANDARD
>>> #&END DIAGONALIZATION
>>>
>>> # ADDED_MOS 30
>>> #
>>> # &SMEAR ON
>>> # METHOD FERMI_DIRAC
>>> # ELECTRONIC_TEMPERATURE [K] 300
>>> #&END SMEAR
>>>
>>> # &MIXING
>>> # METHOD BROYDEN_MIXING
>>> # ALPHA 0.4
>>> # BETA 0.5
>>> # NBROYDEN 8
>>> # &END MIXING
>>> &END SCF
>>>
>>> &XC
>>> &XC_FUNCTIONAL PBE
>>> &END XC_FUNCTIONAL
>>> &END XC
>>>
>>> &KPOINTS
>>> EPS_GEO 1.0E-5
>>> SCHEME MONKHORST 3 3 3
>>> &END KPOINTS
>>> &END DFT
>>>
>>> &PRINT
>>> &TOTAL_NUMBERS ON
>>> &END TOTAL_NUMBERS
>>> &END PRINT
>>>
>>> STRESS_TENSOR ANALYTICAL
>>> &END FORCE_EVAL
>>>
>>> &MOTION
>>> &GEO_OPT
>>> OPTIMIZER LBFGS
>>> TYPE MINIMIZATION
>>> MAX_DR 5.0E-4
>>> MAX_FORCE 5.0E-4
>>> RMS_DR 5.0E-4
>>> RMS_FORCE 5.0E-4
>>> MAX_ITER 500
>>> &END GEO_OPT
>>>
>>> &CELL_OPT
>>> TYPE DIRECT_CELL_OPT
>>> OPTIMIZER LBFGS
>>> KEEP_SYMMETRY
>>> MAX_DR 5.0E-4
>>> MAX_FORCE 1.0E-4
>>> RMS_DR 5.0E-4
>>> RMS_FORCE 5.0E-4
>>> # defaults for p and delta p [bar]
>>> EXTERNAL_PRESSURE 100.0 0.0 0.0 0.0 100.0 0.0 0.0 0.0 100.0
>>> PRESSURE_TOLERANCE 100.0
>>> &END CELL_OPT
>>> &END MOTION
>>>
>>>
>>>
>>>
>>> Thank you,
>>> Huaiyang Sun
>>>
>>>
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