[QE-users] NEB images with different cell parameters possible?

[A. Jain]

Sorry for not being clearer, the 'excited' state in our case is actually 
a metastable state, i.e. a stable state on its own that has undergone 
photoisomerisation via broadband light.

I figured there wasn't variable cell neb. I thought to simply average 
the cell parameters and use them to conduct neb. I guess the geometries 
shouldn't be too affected by the slight change in cell parameters, and 
neb isn't too thrown off by that.

Apoorv

On 2019-09-06 16:00, Paolo Giannozzi wrote:
> Some time ago there was a project of variable-cell NEB, but it went
> nowhere. Anyway: here the problem is not variable-cell NEB but a NEB
> between an initial configuration in the ground state and a final one
> in the excited state, if I understand correctly. This is just plain
> impossible.
> 
> Paolo
> 
> On Fri, Sep 6, 2019 at 11:21 AM Giuseppe Mattioli
> <giuseppe.mattioli at ism.cnr.it> wrote:
> 
>> Dear Apoorv Jain
>> 
>> AFAIK, variable cell NEB is not implemented in QE (yet).
>> HTH
>> Giuseppe
>> 
>> "A. Jain" <aj520 at cam.ac.uk> ha scritto:
>> 
>>> Hi All,
>>> 
>>> I would like to conduct an neb study on my system (ruthenium
>> based
>>> crystals) where photoisomerisation takes place. We would like to
>> 
>>> investigate the mechanism of photoisomerisation. However the
>> ground
>>> state and irradiated states (geometries obtained via accurate xrd
>> 
>>> experiments) have very slightly different cell parameters due to
>> the
>>> magnitude of the photoisomerisation.
>>> 
>>> The Ground State values are :Axis (Ang): A=8.3891, B=12.5019,
>>> C=13.1614. Angles (deg): a=99.481, b=98.613, c=90.27.
>>> Excited state: Axis (Ang): A=8.4845, B=12.4241, C=13.3243. Angles
>> 
>>> (deg): a=101.456, b=98.732, c=91.001.
>>> As you can see the values effectively only change by 1%.
>>> 
>>> So I would like to know if is it possible to conduct neb on
>> images
>>> whose cell parameters also change, ie I would use the ground
>> state
>>> as the starting image and the excited state as the final image? I
>> 
>>> expect the answer is no. If not, has anybody come across a
>> similar
>>> problem or has any suggestions for how I could approach this
>> issue?
>>> 
>>> Thank you for your help.
>>> 
>>> Apoorv Jain (PhD Student)
>>> Department of Physics, University of Cambridge
>>> _______________________________________________
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>> 
>> GIUSEPPE MATTIOLI
>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
>> Via Salaria Km 29,300 - C.P. 10
>> I-00015 - Monterotondo Scalo (RM)
>> Mob (*preferred*) +39 373 7305625
>> Tel + 39 06 90672342 - Fax +39 06 90672316
>> E-mail: <giuseppe.mattioli at ism.cnr.it>
>> 
>> _______________________________________________
>> Quantum ESPRESSO is supported by MaX
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> 
> --
> 
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> 
> 
> 
> Links:
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