Cell Optimization of triclinic cell

[Aniruddha Dive]

Thanks Matt,

Its working correctly now.

On Tuesday, April 17, 2018 at 4:34:13 PM UTC-7, Matt W wrote:
>
> Hi,
>
> you should either specify 
>
> ABC and alpha, beta, gamma
>
> or
>
> give the whole set of vectors, not both.
>
> If the set of A, B, C vectors are given any angles are ignored.
>
> Also, I suspect  your supercell likely isn't large enough. By default cp2k 
> only uses gamma point to sample the Brillouin zone. You should probably use 
> a 2x2x1 supercell to get reasonably accurate results.
>
> Matt
>
> On Wednesday, April 18, 2018 at 12:03:43 AM UTC+1, Aniruddha Dive wrote:
>>
>> Hi All,
>>
>> I am trying to do cell optimization of a SiS2 crystal structure which has 
>> a triclinic symmetry. Below is the section of input file where I specify 
>> the cell vectors and the angles:
>>
>>  &SUBSYS
>>     &CELL
>>       
>>
>>
>>
>>
>> *SYMMETRY TRICLINIC      A 5.58515   0.00000   0.00000      B 0.00000   
>> 6.21427   0.00000      C 0.00000   0.00000  10.92676      ALPHA_BETA_GAMMA 
>> 116.86 113.96 90.00      PERIODIC XYZ*
>>     &END
>>     ! unit cells that are orthorhombic are more efficient with CP2K
>>     ! atom coordinates can be in the &COORD section,
>>     ! or provided as an external file.
>>     &TOPOLOGY
>>        COORD_FILE_FORMAT PDB
>>        COORD_FILE_NAME SiS2_computed.pdb
>>        CONNECTIVITY OFF
>>        &CENTER_COORDINATES
>>        &END CENTER_COORDINATES
>>     &END
>>
>> When I try to run the calculations, in the output file I can see the 
>> correct vectors a,b and c but the angles are still 90.0 90.0 and 90.0. 
>> Below is the portion from output file:
>>
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>> *CELL_TOP| Volume [angstrom^3]:                                          
>> 379.242 CELL_TOP| Vector a [angstrom     5.585     0.000     0.000    |a| 
>> =       5.585 CELL_TOP| Vector b [angstrom     0.000     6.214     0.000    
>> |b| =       6.214 CELL_TOP| Vector c [angstrom     0.000     0.000    
>> 10.927    |c| =      10.927 CELL_TOP| Angle (b,c), alpha 
>> [degree]:                                   90.000 CELL_TOP| Angle (a,c), 
>> beta  [degree]:                                   90.000 CELL_TOP| Angle 
>> (a,b), gamma [degree]:                                   90.000 CELL_TOP| 
>> Requested initial symmetry:                                 
>> TRICLINIC CELL_TOP| Numerically 
>> orthorhombic:                                         YES CELL| Volume 
>> [angstrom^3]:                                              379.242 CELL| 
>> Vector a [angstrom]:       5.585     0.000     0.000    |a| =       
>> 5.585 CELL| Vector b [angstrom]:       0.000     6.214     0.000    |b| 
>> =       6.214 CELL| Vector c [angstrom]:       0.000     0.000    10.927    
>> |c| =      10.927 CELL| Angle (b,c), alpha 
>> [degree]:                                       90.000 CELL| Angle (a,c), 
>> beta  [degree]:                                       90.000 CELL| Angle 
>> (a,b), gamma [degree]:                                       90.000 CELL| 
>> Requested initial symmetry:                                     
>> TRICLINIC CELL| Numerically 
>> orthorhombic:                                             YES CELL_REF| 
>> Volume [angstrom^3]:                                          
>> 379.242 CELL_REF| Vector a [angstrom     5.585     0.000     0.000    |a| 
>> =       5.585 CELL_REF| Vector b [angstrom     0.000     6.214     0.000    
>> |b| =       6.214 CELL_REF| Vector c [angstrom     0.000     0.000    
>> 10.927    |c| =      10.927 CELL_REF| Angle (b,c), alpha 
>> [degree]:                                   90.000 CELL_REF| Angle (a,c), 
>> beta  [degree]:                                   90.000 CELL_REF| Angle 
>> (a,b), gamma [degree]:                                   90.000 CELL_REF| 
>> Requested initial symmetry:                                 
>> TRICLINIC CELL_REF| Numerically 
>> orthorhombic:                                         YES*
>>
>> Because of this the complete geometry of the cell has changed during the 
>> optimization giving me weird results. Please find attached input files as 
>> well as the coordinate file.
>>
>> Kindly let me know how to fix the issue.
>>
>> Regards,
>> Aniruddha M Dive
>> PhD Candidate, Washington State University
>>
>>
>>
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