[CP2K-user] [CP2K:15343] Ar lattice constant calculation

[Fabian Ducry]

cp2k prints "CELL| Vector" after each iteration of the optimizer. From 
this you can calculate the lattice constant.

The lattice constant usually refers to the dimension of a unit cell, 
therefore it does not change when you create a supercell. The cell 
dimensions, however, differ between the unit and supercell.

Fabian

On 12.05.2021 13:42, sumit agrawal wrote:
> Dear Fabian,
>
> Thanks for the quick response. Actually I prepared a lattice structure 
> (2x2x2) in VESTA software. Is it the correct tool to prepare lattice 
> structure, any idea?
>
> I tried again to prepare a lattice structure. So 2x2x2 will contain 32 
> atoms. Then I performed cell_opt in cp2k. I am attaching my coordinate 
> file, input file and out file.
>
> Where will I find the lattice constant in the output file?
>
> One more query: will the lattice constant for 1x1x1 unit cell and 
> nxnxn unit cell be same or different?
>
>
>
>
>
> On Wed, May 12, 2021 at 1:57 PM Fabian Ducry <fabia... at gmail.com 
> <mailto:fabia... at gmail.com>> wrote:
>
>     Dear Sumit
>
>     A supercell of (2x2x2) has to contain 2*2*2=8 times the number of
>     atoms of the unit cell. So It can never have an odd number as in
>     your case 63. You should follow a tutorial on how to prepare such
>     a structure, e.g. with ASE. Here, for example, you find
>     instruction on how to build a crystal:
>     http://exciting-code.org/lithium-atomic-simulation-environment
>     <http://exciting-code.org/lithium-atomic-simulation-environment>.
>     Once you have the ASE Atoms object building the supercell is as
>     easy as atoms*(2,2,2). When you have a correct crystal, make sure
>     that the &CELL section in the cp2k input matches the lattice
>     dimensions of the crystal. You cannot just use an arbitrary number.
>
>     CELL_OPT will optimize both the atom positions as well as the
>     lattice dimensions.
>
>     Fabian
>
>     On 12.05.2021 06:19, sumit agrawal wrote:
>>
>>     Dear Lucas Lodeiro and Fabian,
>>
>>     Thanks for your nice suggestions. I am new to cp2k. I have just
>>     started learning this. I have some query regarding my procedure
>>     for preparation for crystal structure. I am following below
>>     procedure to prepare the crystal structure:
>>
>>     First, I have prepared the crystal structure (2x2x2) with the
>>     lattice dimension a=5.2229 A, b=5.2229 A and c=5.2229 A. It
>>     contains 63 atoms. After that I removed some atoms from x, y and
>>     z directions so that it become periodic in x, y and z direction.
>>     After this, it contains 32 atoms.
>>     Now I save this lattice in XYZ format. This will be my
>>     initial coordinate system. Am I correct?
>>
>>     After this I took this coordinate file and ran for the cp2k
>>     calculation.
>>
>>     Now in cp2k calculations for this lattice structure what will be
>>     my cube size? (Here you mention it will not be 20 A. )
>>
>>     One more query, here I am starting with a lattice dimension with
>>     5.2229 A . So after Cell_OPTIMIZATION, will the geometry of my
>>     crystal change or not?
>>
>>     Yes, dispersion correction must be required for this type of
>>     calculation, I will do that.
>>
>>     Here I am attaching my crystal structure images.
>>
>>
>>
>>     Thanks
>>     Sumit
>>
>>
>>
>>     On Tue, May 11, 2021 at 11:02 PM Lucas Lodeiro
>>     <eluni... at gmail.com <mailto:eluni... at gmail.com>> wrote:
>>
>>         Hi Sumit,
>>
>>         First of all, you cannot find the lattice constant with this
>>         type of calculation. You ran an ENERGY calculation. If you
>>         want to do it, you need to run a CELL_OPT calculation.
>>         In your current calculation, you use a 20 A lattice constant
>>         cube. Also, I think your initial cell dimension is not
>>         correct, since the lattice constant of Argon is 5.26 A, then
>>         a 2x2x2 supercell is not 20 A sized. Also, your system has 63
>>         atoms... ¿?.
>>
>>         Other related topics are: a 2x2x2 supercell is not
>>         sufficient to compute a periodical Argon system... You need a
>>         bigger supercell, or use kpoints. Also, as this system just
>>         interacts by dispersion, probably the PBE functional is not
>>         sufficient at all. You need to account the dispersion terms
>>         by means of Grimes D3 or other.
>>
>>         Regards
>>
>>         El mar, 11 may 2021 a las 14:08, sumit agrawal
>>         (<sumitag... at gmail.com
>>         <mailto:sumitag... at gmail.com>>) escribió:
>>
>>             Hii everyone,
>>
>>             I want to calculate a lattice constant for the Ar crystal
>>             of (2*2*2 unit cell). I am attaching my input and out
>>             files. Where I will find the lattice constant ?
>>
>>             Please help me!!
>>
>>
>>             -- 
>>             You received this message because you are subscribed to
>>             the Google Groups "cp2k" group.
>>             To unsubscribe from this group and stop receiving emails
>>             from it, send an email to
>>             cp... at googlegroups.com
>>             <mailto:cp... at googlegroups.com>.
>>             To view this discussion on the web visit
>>             https://groups.google.com/d/msgid/cp2k/CALSDoYbVb-H5Bp3K5twhNotUESTnixKMaWBnBKNMZr7xzC2%3DSw%40mail.gmail.com
>>             <https://groups.google.com/d/msgid/cp2k/CALSDoYbVb-H5Bp3K5twhNotUESTnixKMaWBnBKNMZr7xzC2%3DSw%40mail.gmail.com?utm_medium=email&utm_source=footer>.
>>
>>         -- 
>>         You received this message because you are subscribed to the
>>         Google Groups "cp2k" group.
>>         To unsubscribe from this group and stop receiving emails from
>>         it, send an email to cp... at googlegroups.com
>>         <mailto:cp... at googlegroups.com>.
>>         To view this discussion on the web visit
>>         https://groups.google.com/d/msgid/cp2k/CAOFT4PKMq7MQYztPnmT3GL5zaPS%3DQErOF4RWR1ch3zmT2gnDEg%40mail.gmail.com
>>         <https://groups.google.com/d/msgid/cp2k/CAOFT4PKMq7MQYztPnmT3GL5zaPS%3DQErOF4RWR1ch3zmT2gnDEg%40mail.gmail.com?utm_medium=email&utm_source=footer>.
>>
>>     -- 
>>     You received this message because you are subscribed to the
>>     Google Groups "cp2k" group.
>>     To unsubscribe from this group and stop receiving emails from it,
>>     send an email to cp... at googlegroups.com
>>     <mailto:cp... at googlegroups.com>.
>>     To view this discussion on the web visit
>>     https://groups.google.com/d/msgid/cp2k/CALSDoYaG6E_PftB%2Bj2xsfsbbfmaFvoW0VvZUxT1CS2kOoz1Rzg%40mail.gmail.com
>>     <https://groups.google.com/d/msgid/cp2k/CALSDoYaG6E_PftB%2Bj2xsfsbbfmaFvoW0VvZUxT1CS2kOoz1Rzg%40mail.gmail.com?utm_medium=email&utm_source=footer>.
>     -- 
>     You received this message because you are subscribed to the Google
>     Groups "cp2k" group.
>     To unsubscribe from this group and stop receiving emails from it,
>     send an email to cp... at googlegroups.com
>     <mailto:cp... at googlegroups.com>.
>     To view this discussion on the web visit
>     https://groups.google.com/d/msgid/cp2k/8845fe89-4df1-745e-b8a9-5f536e6434f0%40gmail.com
>     <https://groups.google.com/d/msgid/cp2k/8845fe89-4df1-745e-b8a9-5f536e6434f0%40gmail.com?utm_medium=email&utm_source=footer>.
>
> -- 
> You received this message because you are subscribed to the Google 
> Groups "cp2k" group.
> To unsubscribe from this group and stop receiving emails from it, send 
> an email to cp... at googlegroups.com 
> <mailto:cp... at googlegroups.com>.
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/cp2k/CALSDoYbEU_9OwK%3DMBiOjwBmbb6Lm%2BtiyRCKgtHxTNhK%3DV_gpQw%40mail.gmail.com 
> <https://groups.google.com/d/msgid/cp2k/CALSDoYbEU_9OwK%3DMBiOjwBmbb6Lm%2BtiyRCKgtHxTNhK%3DV_gpQw%40mail.gmail.com?utm_medium=email&utm_source=footer>.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210512/f4946348/attachment.htm>