[CP2K:5603] Re: Bulk Nickel (and possibly other newbie questions)

Ralph Koitz ralph... at gmail.com
Sat Aug 16 01:04:25 CEST 2014


I used the following
      BASIS_SET  DZVP-MOLOPT-SR-GTH
      POTENTIAL  GTH-PBE-q18

and set the multiplicity to n(atom)+1, basically s=1/2 for each atom in the
supercell.


On Fri, Aug 15, 2014 at 3:14 PM, Alex <nedo... at gmail.com> wrote:

> Hi Ralph,
>
> This is all very useful, thanks a bunch. I added cell multiplicity
> explicitly, as you suggested.
> Since I am not the owner of the installation (I'm running it on a remote
> cluster), I won't be able to compile anything myself, so I'll stick with
> what's there now (I think we have Debian binaries). I am looking at the
> reference you provided... For PBE/revPBE XC, what potential and basis did
> you use, exactly (assuming they are part of the package)? Also, did you use
> s=1/2 for the multiplicity in this case, i.e. the MULTIPLICITY param would
> be 2?..
>
> Thank you,
>
> Alex
>
>
> On Friday, August 15, 2014 3:36:47 PM UTC-6, Ralph wrote:
>
>> Hi,
>>
>> To use spin polarization, you should specify the keyword UKS in the DFT
>> section and define a MULTIPLICITY.
>> You may also want to turn on RELAX_MULTIPLICITY in that section.
>>
>> To use a supercell, you can either manually repeat your coordinates and
>> load the entire supercell as input coordinates, or specify
>> MULTIPLE_UNIT_CELL in both the CELL and TOPOLOGY sections of the SUBSYS.
>> A 6x6x6 supercell should be okay to start out with, but you may want to
>> check convergence.
>>
>> We have had decent experience with revPBE as an XC Functional for Ni [1].
>> BEEFvdW, a more recent addition to cp2k also gives very good bulk nickel,
>> but it's currently somewhat of a beta-version and you need to compile with
>> libxc to get it to work.
>>
>> Best,
>> Ralph
>>
>> [1] Gomez-Diaz et al, Theor Chim Acta, 2013
>>
>> On Fri, Aug 15, 2014 at 2:24 PM, Alex <ned... at gmail.com> wrote:
>>
>>>  Also, I just redid the calculation with
>>>
>>>     BASIS_SET DZV-GTH-PADE-q18
>>>    POTENTIAL GTH-PADE-q18
>>>
>>> Same energy within I believe five decimal places. As far as the correct
>>> choice of the XC-potential-basis combination, what would be better in my
>>> case? As I've said before, I am really new to this... Any reference to that
>>> effect would be great.
>>>
>>> Thank you.
>>>
>>> On Friday, August 15, 2014 3:05:37 PM UTC-6, Marcella Iannuzzi wrote:
>>>>
>>>> Hi
>>>>
>>>> Just few remarks.
>>>>
>>>> For the fcc bulk Ni energy, you need to construct a supercell, since
>>>> there is no k-point sampling,
>>>> and check the convergence of the result with system size.
>>>>
>>>> PADE is probably not an optimal choice for the XC functional, anyway,
>>>> you should use consistent potential and basis set,
>>>> i.e. for the same number of valence electrons (in your input, the PP is
>>>> for 10 v.e. and the BS for 18)
>>>>
>>>> If you don't specify in in the input, no spin polarisation is
>>>> considered.
>>>>
>>>> Regards
>>>>
>>>> Marcella
>>>>
>>>>
>>>> On Friday, August 15, 2014 10:19:59 PM UTC+2, Alex wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I am very new to DFT calculations, let alone CP2k, so some level of
>>>>> idiocy on my part should be expected.
>>>>> As a simple test, I am trying to calculate the binding energy of a Ni
>>>>> atom in a bulk crystal. The relevant portion of the input shown below:
>>>>>
>>>>> ***
>>>>> &GLOBAL
>>>>>   PROJECT Ni_inp_test
>>>>>   RUN_TYPE ENERGY_FORCE
>>>>>   PRINT_LEVEL LOW
>>>>> &END GLOBAL
>>>>> &FORCE_EVAL
>>>>>   METHOD Quickstep
>>>>>   &SUBSYS
>>>>>     &KIND Ni
>>>>>       ELEMENT Ni
>>>>>       BASIS_SET DZV-GTH-PADE-q18
>>>>>       POTENTIAL GTH-PADE-q10
>>>>>     &END KIND
>>>>>     &CELL
>>>>>       A     1.765000    1.765000    0.000000
>>>>>       B     0.000000    1.765000    1.765000
>>>>>       C    1.765000    0.000000    1.765000
>>>>>       PERIODIC XYZ
>>>>>     &END CELL
>>>>>     &COORD
>>>>>       Ni    0.000000000    0.000000000    0.000000000
>>>>>     &END COORD
>>>>>   &END SUBSYS
>>>>>   &DFT
>>>>>     BASIS_SET_FILE_NAME  BASIS_SET
>>>>>     POTENTIAL_FILE_NAME  GTH_POTENTIALS
>>>>>     &QS
>>>>>       EPS_DEFAULT 1.0E-10
>>>>>     &END QS
>>>>>     &MGRID
>>>>>       NGRIDS 4
>>>>>       CUTOFF 300
>>>>>       REL_CUTOFF 60
>>>>>     &END MGRID
>>>>>     &XC
>>>>>       &XC_FUNCTIONAL PADE
>>>>>       &END XC_FUNCTIONAL
>>>>>     &END XC
>>>>>     &SCF
>>>>>       SCF_GUESS ATOMIC
>>>>>       EPS_SCF 1.0E-7
>>>>>       MAX_SCF 300
>>>>>       ADDED_MOS 10
>>>>>       &DIAGONALIZATION  ON
>>>>>         ALGORITHM STANDARD
>>>>>       &END DIAGONALIZATION
>>>>>       &MIXING  T
>>>>>         METHOD BROYDEN_MIXING
>>>>>         ALPHA 0.4
>>>>>         NBROYDEN 8
>>>>>       &END MIXING
>>>>>       &SMEAR ON
>>>>>         METHOD FERMI_DIRAC
>>>>>         ELECTRONIC_TEMPERATURE [K] 300
>>>>>       &END SMEAR
>>>>>     &END SCF
>>>>>   &END DFT
>>>>>   &PRINT
>>>>>     &FORCES ON
>>>>>     &END FORCES
>>>>>   &END PRINT
>>>>> &END FORCE_EVAL
>>>>>
>>>>> ***
>>>>>
>>>>> This yields a total energy of E1=-35.155 a.u. after convergence.
>>>>>
>>>>> Then I decided to calculate the "vacuum" energy of an isolated atom,
>>>>> input below:
>>>>>
>>>>> &GLOBAL
>>>>>   PROJECT Ni_inp_test
>>>>>   RUN_TYPE ENERGY_FORCE
>>>>>   PRINT_LEVEL LOW
>>>>> &END GLOBAL
>>>>> &FORCE_EVAL
>>>>>   METHOD Quickstep
>>>>>   &SUBSYS
>>>>>     &KIND Ni
>>>>>       ELEMENT Ni
>>>>>       BASIS_SET DZV-GTH-PADE-q18
>>>>>       POTENTIAL GTH-PADE-q10
>>>>>     &END KIND
>>>>>     &CELL
>>>>>       A     30.00000    0.000000    0.000000
>>>>>       B     0.000000    30.00000    0.000000
>>>>>       C    0.000000    0.000000    30.00000
>>>>>     &END CELL
>>>>>     &COORD
>>>>>       Ni    0.000000000    0.000000000    0.000000000
>>>>>     &END COORD
>>>>>   &END SUBSYS
>>>>>   &DFT
>>>>>     BASIS_SET_FILE_NAME  BASIS_SET
>>>>>     POTENTIAL_FILE_NAME  GTH_POTENTIALS
>>>>>     &QS
>>>>>       EPS_DEFAULT 1.0E-10
>>>>>     &END QS
>>>>>     &MGRID
>>>>>       NGRIDS 4
>>>>>       CUTOFF 300
>>>>>       REL_CUTOFF 60
>>>>>     &END MGRID
>>>>>     &XC
>>>>>       &XC_FUNCTIONAL PADE
>>>>>       &END XC_FUNCTIONAL
>>>>>     &END XC
>>>>>     &SCF
>>>>>       SCF_GUESS ATOMIC
>>>>>       EPS_SCF 1.0E-7
>>>>>       MAX_SCF 300
>>>>>       ADDED_MOS 10
>>>>>       &DIAGONALIZATION  ON
>>>>>         ALGORITHM STANDARD
>>>>>       &END DIAGONALIZATION
>>>>>       &MIXING  T
>>>>>         METHOD BROYDEN_MIXING
>>>>>         ALPHA 0.4
>>>>>         NBROYDEN 8
>>>>>       &END MIXING
>>>>>       &SMEAR ON
>>>>>         METHOD FERMI_DIRAC
>>>>>         ELECTRONIC_TEMPERATURE [K] 300
>>>>>       &END SMEAR
>>>>>     &END SCF
>>>>>   &END DFT
>>>>>   &PRINT
>>>>>     &FORCES ON
>>>>>     &END FORCES
>>>>>   &END PRINT
>>>>> &END FORCE_EVAL
>>>>>
>>>>> ***
>>>>>
>>>>> This also converges and yields a total energy E2=-34.555 a.u.
>>>>>
>>>>>
>>>>> Hence, my questions:
>>>>>
>>>>> 1. Is this even the correct way of calculating what I want, including
>>>>> the energy calculations, XC functional, and basis?
>>>>> 2. Should the spin properties be explicitly set in the input? There
>>>>> are none now.
>>>>> 3. Am I setting up the FCC lattice correctly (first input file)? My
>>>>> translation vectors are set by the ABC values, but I have no idea whether
>>>>> this is right.
>>>>> 4. If the first simulation yields the total energy of the system and
>>>>> the FCC lattice implies 12 nearest neighbors, then removing the center
>>>>> would change the total energy by (E1-E2)/6, which isn't the experimental
>>>>> -4.4 eV. Am I completely off track here? :)
>>>>>
>>>>> Thanks a lot!
>>>>>
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