[CP2K:9464] Re: Hybrid functional calculation results show large difference with VASP
Xiaoming Wang
wxia... at gmail.com
Thu Sep 21 15:51:57 UTC 2017
Hi Ling,
Here is my input for PBE0 calculation without ADMM.
-------------------------------------------------------------------------------
&GLOBAL
PROJECT_NAME Cs2InAgCl6
RUN_TYPE ENERGY
PRINT_LEVEL LOW
&END GLOBAL
&FORCE_EVAL
METHOD QS
&DFT
BASIS_SET_FILE_NAME BASIS_MOLOPT
POTENTIAL_FILE_NAME GTH_POTENTIALS
WFN_RESTART_FILE_NAME pbe.wfn
&QS
EPS_DEFAULT 1.0e-10
EPS_PGF_ORB 1.0e-6
&END
&MGRID
CUTOFF 250
REL_CUTOFF 50
&END MGRID
&XC
&XC_FUNCTIONAL
&PBE
SCALE_X 0.75
SCALE_C 1.0
&END PBE
&PBE_HOLE_T_C_LR
CUTOFF_RADIUS 5
SCALE_X 0.25
&END PBE_HOLE_T_C_LR
&END XC_FUNCTIONAL
&HF
FRACTION 0.25
&SCREENING
EPS_SCHWARZ 1.0e-6
&END SCREENING
&INTERACTION_POTENTIAL
POTENTIAL_TYPE TRUNCATED
CUTOFF_RADIUS 5
T_C_G_DATA ./t_c_g.dat
&END INTERACTION_POTENTIAL
&MEMORY
MAX_MEMORY 3200
EPS_STORAGE_SCALING 0.1
&END MEMORY
&END HF
&END XC
&SCF
MAX_SCF 100
EPS_SCF 1.0e-6
CHOLESKY INVERSE
SCF_GUESS RESTART
&DIAGONALIZATION
ALGORITHM STANDARD
&END DIAGONALIZATION
&MIXING
METHOD PULAY_MIXING
&END SCF
&PRINT
&MO_CUBES
WRITE_CUBE F
NHOMO 1
NLUMO 1
&END MO_CUBES
&END PRINT
&END DFT
&SUBSYS
&CELL
ABC [angstrom] 10.5345 10.5345 10.5345
ALPHA_BETA_GAMMA [deg] 90 90 90
PERIODIC XYZ
SYMMETRY CUBIC
&END CELL
&COORD
............
SCALED T
&END COORD
&KIND Cs
ELEMENT Cs
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE-q9
&END KIND
&KIND In
ELEMENT In
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE-q13
&END KIND
&KIND Ag
ELEMENT Ag
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE-q11
&END KIND
&KIND Cl
ELEMENT Cl
BASIS_SET DZVP-MOLOPT-SR-GTH
POTENTIAL GTH-PBE-q7
&END KIND
&END SUBSYS
&END FORCE_EVAL
I have the PROCAR file from VASP calculations. I need to find a way to get
the PDOS from cp2k. I will post the results later.
Best,
Xiaoming
On Thursday, September 21, 2017 at 11:10:15 AM UTC-4, S Ling wrote:
>
> Hi
>
> I am not sure how you ran the PBE0 calculation without ADMM using the
> MOLOPT basis sets, which were not designed for hybrid DFT calculations.
> Hybrid DFT calculations without ADMM for your Cs2InAgCl6 system will use a
> lot of memory, and as Prof Hutter suggested earlier, it will also be
> 100~1000 times slower.
>
> "without ADMM basis sets I have SCF convergence issue if I don't use the
> Coulomb truncation method, both for OT and diagonalization, the SCF didn't
> tend to converge. Why is that?"
>
> Please have a look at the two papers below, which answer your question:
>
> http://pubs.acs.org/doi/abs/10.1021/ct900494g
> http://aip.scitation.org/doi/10.1063/1.2931945
>
> For the PBE0 band gaps calculated using different codes, I can see for
> binary systems, the differences are at the order of 0.2 eV or smaller,
> which I think is not something totally unexpected, because of the different
> HFX implementation strategies, different basis sets and different
> pseudopotentials used by the two codes. If you try a third code based on
> atomic orbital basis sets, you may also get different answers. In addition,
> similar results at PBE level doesn't necessarily mean the numbers at PBE0
> level will or should be similar as well. From computational point of
> view, compounds involving d block elements are usually more difficult to
> deal with than compounds involving only s and p block elements. As you
> mentioned earlier, it could simply be the case that the differences in
> binary systems added up in your quaternary system. It may be useful to
> check what numbers the two codes will give for the ternary system, before
> we look at the more complicated quaternary system. The VASP/PROCAR and
> CP2K/PDOS analysis will tell us what are the nature of the states at the
> top of the valence band and at the bottom of the conduction band, which
> will help us to understand the difference between the two codes.
>
> SL
>
>
> On 21 September 2017 at 14:57, Xiaoming Wang <wxi... at gmail.com> wrote:
>
>> I'd like to add that my PBE0 calculation without ADMM basis sets has been
>> done. I tested 10*10*10 Cs2InAgCl6, which is the system of my original
>> post. The band gap is 2.52 and 2.50 eV for with and without ADMM. So it
>> seems not the ADMM basis problem?
>> I have another question that without ADMM basis sets I have SCF
>> convergence issue if I don't use the Coulomb truncation method, both for OT
>> and diagonalization, the SCF didn't tend to converge. Why is that? (The
>> calculation is fine with TC.)
>>
>> Best,
>>
>>
>> On Thursday, September 21, 2017 at 8:54:49 AM UTC-4, Xiaoming Wang wrote:
>>>
>>> Hi,
>>>
>>> I am sorry for the confusing formula. It is actually Cs2InAgCl6, in
>>> which Ag is +1. When you are fitting the ADMM basis sets, what's the
>>> reference system for Ag? Is it in solid environment? Is it possible for me
>>> to fit the ADMM basis myself based on my vasp calculations? Well, maybe it
>>> is too difficult for me, since I am new to cp2k. Btw, do the ADMM basis
>>> sets depend on the oxidation states of the elements involved? If that's the
>>> case, there would be problems dealing with different systems with the same
>>> basis sets. Moreover, the oxidation state is an arbitrary quantity
>>> depending on the charge partition scheme. The oxidation state may be slight
>>> different even for the systems which are assumed to be +1 for a particular
>>> element, for example.
>>>
>>> Best,
>>>
>>> Xiaoming
>>>
>>> On Thursday, September 21, 2017 at 6:17:45 AM UTC-4, S Ling wrote:
>>>>
>>>> Hi
>>>>
>>>> Can you confirm the chemical formula of your CsInAgCl system? I looked
>>>> through the ICSD database, and the only related compound which I can find
>>>> is CsAgInF6, in which Ag is in an uncommon +2 oxidation state (in your
>>>> benchmark test, you looked at AgCl, in which Ag is in the common +1
>>>> oxidation state). If this is the case for CsInAgCl6, there is a possibility
>>>> that your CP2K/PBE0 and VASP/PBE0 calculations may have converged to
>>>> slightly different SCF solutions. You can check this by comparing the
>>>> orbital occupation numbers from your VASP/PROCAR and from the CP2K/PDOS
>>>> analysis. Another possibility is that the ADMM basis sets are indeed not
>>>> good enough to describe Ag2+ (I have only considered Ag+ when I was fitting
>>>> the ADMM basis sets of Ag).
>>>>
>>>> SL
>>>>
>>>>
>>>>
>>>> On 21 September 2017 at 03:52, Xiaoming Wang <wxi... at gmail.com> wrote:
>>>>
>>>>> Hi, Can you see it this time?
>>>>>
>>>>>
>>>>> <https://lh3.googleusercontent.com/-f1GOmo2FRic/WcMpJhTURnI/AAAAAAAAGcU/MqO1xDMjsmQIV1PsgFDq5Aq_IqaPdz-CQCLcBGAs/s1600/benchmark.PNG>
>>>>>
>>>>>
>>>>> On Wednesday, September 20, 2017 at 10:45:10 PM UTC-4, Matt W wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I only see the check for InCl3, not the main system?
>>>>>>
>>>>>> Matt
>>>>>>
>>>>>> On Thursday, September 21, 2017 at 10:36:15 AM UTC+8, Xiaoming Wang
>>>>>> wrote:
>>>>>>>
>>>>>>> Hi Matt,
>>>>>>>
>>>>>>> Actually I also did the calculation for a supercell of 21*21*21 with
>>>>>>> 320 atoms. PBE0 without TC are also tested, please see my benchmark tests
>>>>>>> in previous post (attachment in reply to Ling).
>>>>>>>
>>>>>>> Best,
>>>>>>> Xiaoming
>>>>>>>
>>>>>>>
>>>>>>> On Wednesday, September 20, 2017 at 10:27:48 PM UTC-4, Matt W wrote:
>>>>>>>>
>>>>>>>> That ADMM basis is already pretty large, so whilst it might be the
>>>>>>>> problem, first I'd check the cell size.
>>>>>>>>
>>>>>>>> Can you build a cell about 15 x 15 x 15 A or larger to allow you to
>>>>>>>> extend the range of the hybrid out to 6 or 7 A?
>>>>>>>>
>>>>>>>> You are truncating at about 5.25 A, which might not be enough to be
>>>>>>>> fully converged (note VASP won't be doing this as it works in K space).
>>>>>>>>
>>>>>>>> Matt
>>>>>>>>
>>>>>>>> On Thursday, September 21, 2017 at 8:36:29 AM UTC+8, Xiaoming Wang
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> Hi Ling,
>>>>>>>>>
>>>>>>>>> Thanks for your comments. I have attached my benchmark results
>>>>>>>>> here. Based on my tests, it seems that the ADMM basis set size is not so
>>>>>>>>> important for ionic crystals. One can get reasonable results even with
>>>>>>>>> smallest basis sets. Btw, the cutoff and rel_cutoff used are well converged
>>>>>>>>> values for my target property. So I think there is still room to improve
>>>>>>>>> the ADMM basis for Ag and In (with semicore d states in the valence). To
>>>>>>>>> check whether it is the problem of Ag and In ADMM basis, the simplest way
>>>>>>>>> is to do the PBE0 calculations without ADMM. But the calculation takes me
>>>>>>>>> too long time, as also pointed out by Juerg. I suspect if it is possible to
>>>>>>>>> do HFX without ADMM using MOLOPT basis sets.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Best,
>>>>>>>>> Xiaoming
>>>>>>>>>
>>>>>>>>> On Wednesday, September 20, 2017 at 6:20:09 AM UTC-4, S Ling wrote:
>>>>>>>>>>
>>>>>>>>>> Hi
>>>>>>>>>>
>>>>>>>>>> I am not sure whether you are using the same ADMM basis sets (see
>>>>>>>>>> your initial input) for these new test calculations. One thing which I can
>>>>>>>>>> see is that you are not using the largest available ADMM basis sets for
>>>>>>>>>> some of the elements, e.g. the largest available ADMM basis sets for Cl, Ag
>>>>>>>>>> and In are pFIT3, FIT12 and FIT13, respectively. Taking In as an example,
>>>>>>>>>> the FIT13 ADMM basis set of In contains more p and d functions than FIT11,
>>>>>>>>>> which may be important for your system.
>>>>>>>>>>
>>>>>>>>>> You mentioned a few different functionals, including PBE, PBE0
>>>>>>>>>> and HSE06, and you have run quite a lot of benchmark tests. It would help
>>>>>>>>>> if you can tabulate all the numbers you have got (including the reference),
>>>>>>>>>> so we can understand your problem better.
>>>>>>>>>>
>>>>>>>>>> In addition, I can see you're using a CUTOFF of 250 Ry. Please
>>>>>>>>>> also check whether your calculation is converged with respect to this
>>>>>>>>>> parameter.
>>>>>>>>>>
>>>>>>>>>> Please also keep in mind that CP2K and VASP use different
>>>>>>>>>> pseudopotentials and basis sets. I wouldn't expect the two codes to give
>>>>>>>>>> the same numbers for your target properties. If you look into literatures,
>>>>>>>>>> you will also find people reporting different numbers for the same property
>>>>>>>>>> using the same method and code.
>>>>>>>>>>
>>>>>>>>>> SL
>>>>>>>>>>
>>>>>>>>>>
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>
>
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