[CP2K:1782] Re: non-orthorhomic variable cell optimization

[Teodoro Laino]

Hi Rad,
actually, there was a bug when handling triclinic cells (in the 
optimization module).
The bug fix is in the CVS.
Thanks,
Teo

Rad wrote:
> Dear Monica,
>
> Thank you for your response and I really appreciate it. I would like
> to clarify further about my earlier posting as it relates to the
> behavior of the variable cell optimization module.
>
> We are getting reasonable results using the variable cell optimization
> module when it comes to non-monoclinic cells. But We have observed
> consistently in the case of triclinic cells is a change in the lattice
> vectors from the given input even before taking an optimization step.
>  It is as if the module is starting with a different initial
> configuration.
>
> Our intention is to understand the process the module follows so that
> we can be comfortable with the final output it produces. For example,
> in one of our studies we gave the following input:
>
> In this case we are providing the experimental lattice configuration
> as the input.
>
>  CELL| Vector a [ANGSTROM]:       9.814     0.000     0.000    |
> a|      =       9.814
>  CELL| Vector b [ANGSTROM]:       0.424     9.038     0.000    |b|
> =       9.048
>  CELL| Vector c [ANGSTROM]:       1.575     0.001    20.279    |c|
> =      20.340
>  CELL| Angle (b,c)
> [degree]:                                              89.790
>  CELL| Angle (a,c)
> [degree]:                                              85.559
>  CELL| Angle (a,b)
> [degree]:                                              87.314
>
> Then after the initial set up the module prints the following
> configuration at the 0th step: (This 0th step is before any prior
> calculation has happened)
> ANGSTROM**3]:                                            1795.645
>  CELL| Vector a [ANGSTROM]:       9.807     0.000     0.000    |a|
> =       9.807
>  CELL| Vector b [ANGSTROM]:       0.424     9.031     0.000    |b|
> =       9.041
>  CELL| Vector c [ANGSTROM]:       1.575    -0.001    20.276    |c|
> =      20.337
>  CELL| Angle (b,c)
> [degree]:                                              89.795
>  CELL| Angle (a,c)
> [degree]:                                              85.559
>  CELL| Angle (a,b)
> [degree]:                                              87.312
>
> This strange switch in the initial geometry is happening only in the
> case of triclinic cells. In addition, the final output volume is off
> by more than 10% in some cases. This is what prompted us to go over
> the output in detail and come up with a pattern.
> It would help us understand and be comfortable with the results if we
> know what is happening at the 0th step and what prompts the change in
> the configuration only for monoclinic cells.
>
> If the developers can take a look at the pattern and provide us with
> any suggestions we would appreciate it.
>
> Thanks
> Rad
>
>
>
> On Feb 13, 9:33 am, monica <monic... at phys.chem.ethz.ch> wrote:
>   
>> Dear Rad,
>>
>> I was running recently several triclinic cell optimization jobs
>> (although the angles are very close to 90), with variable hydrostatic
>> pressure (0-20 GPa), and it seemed to work: when comparing the volume
>> with similar orthorhombic cell, optimized manually (energy volume
>> curve). See output below for example. In my case, when the cell was
>> already close to the minimum, only minor changes occurred.
>>
>> Monica
>>
>> output for example
>>  CELL| Volume
>> [ANGSTROM**3]:                                            1798.737
>>  CELL| Vector a [ANGSTROM]:       9.814     0.000     0.000    |a|
>> =       9.814
>>  CELL| Vector b [ANGSTROM]:       0.424     9.038     0.000    |b|
>> =       9.048
>>  CELL| Vector c [ANGSTROM]:       1.575     0.001    20.279    |c|
>> =      20.340
>>  CELL| Angle (b,c)
>> [degree]:                                              89.790
>>  CELL| Angle (a,c)
>> [degree]:                                              85.559
>>  CELL| Angle (a,b)
>> [degree]:                                              87.314
>>  CELL| Grid size for subcell
>> generation                                    2.000
>>  CELL| Volume
>> [ANGSTROM**3]:                                            1795.645
>>  CELL| Vector a [ANGSTROM]:       9.807     0.000     0.000    |a|
>> =       9.807
>>  CELL| Vector b [ANGSTROM]:       0.424     9.031     0.000    |b|
>> =       9.041
>>  CELL| Vector c [ANGSTROM]:       1.575    -0.001    20.276    |c|
>> =      20.337
>>  CELL| Angle (b,c)
>> [degree]:                                              89.795
>>  CELL| Angle (a,c)
>> [degree]:                                              85.559
>>  CELL| Angle (a,b)
>> [degree]:                                              87.312
>>  CELL| Grid size for subcell
>> generation                                    2.000
>>  CELL| Volume
>> [ANGSTROM**3]:                                            1785.878
>>  CELL| Vector a [ANGSTROM]:       9.783     0.000     0.000    |a|
>> =       9.783
>>  CELL| Vector b [ANGSTROM]:       0.424     9.008     0.000    |b|
>> =       9.018
>>  CELL| Vector c [ANGSTROM]:       1.574    -0.006    20.266    |c|
>> =      20.327
>>  CELL| Angle (b,c)
>> [degree]:                                              89.810
>>  CELL| Angle (a,c)
>> [degree]:                                              85.560
>>  CELL| Angle (a,b)
>> [degree]:                                              87.307
>>
>> On Feb 11, 10:47 pm, Rad <rad.... at arl.army.mil> wrote:
>>
>>
>>
>>     
>>> Hello everybody,
>>>       
>>> We seem to be having an issue with non-orthorhombic cell optimization
>>> when the lattice has all the three angles other than 90 degrees. Here
>>> is what appears to be happening: After the initial set up, the module
>>> Changes the lattice vectors by keeping the lengths the same but the
>>> angles are slightly different. This happens only when all the angles
>>> are not 90-degrees. The regtest for non-orthorhombic includes only one
>>> angle 120 and the rest are 90s. So the scenario I described might be
>>> missed out. This issue we have observed in several executables we have
>>> built over the last several months and on multiple architectures.
>>>       
>>> ===========================================================================­=======
>>> Here is the output just after the set up which is the same as the
>>> input:
>>> CELL| Volume
>>> [ANGSTROM**3]:                                             442.524
>>>  CELL| Vector a [ANGSTROM]:       9.010     0.000     0.000    |a|
>>> =       9.010
>>>  CELL| Vector b [ANGSTROM]:      -4.510     7.821     0.000    |b|
>>> =       9.028
>>>  CELL| Vector c [ANGSTROM]:      -0.216    -2.630     6.280    |c|
>>> =       6.812
>>>  CELL| Angle (b,c)
>>> [degree]:                                             108.580
>>>  CELL| Angle (a,c)
>>> [degree]:                                              91.820
>>>  CELL| Angle (a,b)
>>> [degree]:                                             119.970
>>>       
>>> Here is when it got changed just before the first step of the
>>> optimization:
>>>       
>>>  CELL| Volume
>>> [ANGSTROM**3]:                                             449.960
>>>  CELL| Vector a [ANGSTROM]:       9.010     0.000     0.000    |a|
>>> =       9.010
>>>  CELL| Vector b [ANGSTROM]:      -4.510     7.821     0.000    |b|
>>> =       9.028
>>>  CELL| Vector c [ANGSTROM]:      -0.216    -2.363     6.386    |c|
>>> =       6.812
>>>  CELL| Angle (b,c)
>>> [degree]:                                             106.534
>>>  CELL| Angle (a,c)
>>> [degree]:                                              91.820
>>>  CELL| Angle (a,b)
>>> [degree]:                                             119.970
>>>  CELL| Grid size for subcell
>>> generation                                    2.000
>>>       
>>>  --------  Informations at step =     0 ------------
>>>   Optimization Method        =                   SD
>>>   Total Energy               =      -386.4717739715
>>>   Internal Pressure [bar]    =     18296.7247113471
>>>  ---------------------------------------------------
>>>       
>>>  --------------------------
>>>  OPTIMIZATION STEP:      1
>>> ===========================================================================­======
>>> Could someone please take a look at this issue and let me know what
>>> might be the issue.
>>>       
>>> Thanks
>>> Rad- Hide quoted text -
>>>       
>> - Show quoted text -
>>     
> >
>