Material simulation

[tom.chau...@gmail.com]

Dear Vampire Users, 

I am completely new to crystallography and must use the Vampire code to make a Curie temperature simulation with the pyrrhotite Fe7S8. 

Has anyone ever done it ? Can someone help me to implement the material file in my case, as well as the unit cell file if needed ?

Thanks in advance for your help

[gabo...@gmail.com]

From looking at [1] and [2], Fe7S8, unfortunately, looks like it has a hexagonal unit cell that is non-orthogonal with angle γ = 120°.

Non-orthogonal unit cells are not support yet when running a parallel VAMPIRE calculation.  For more about that, refer to the references within the post at [3].  The parallel might be needed to have a feasible runtime for the calculation.

As seen at [4], a user asked about the usage case with serial in Feb 2024, but we haven't seen any response or clarification from the VAMPIRE developers. 

As you know from the VAMPIRE 6.0 manual on page 34 [5], the unit cell file (ucf) contains:

# Unit cell size:
ucx ucy ucz
# Unit cell vectors:
ucvxx ucvxy ucvxz
ucvyx ucvyy ucvyz
ucvzx ucvzy ucvzz

You could try setting the vectors to see what happens with today's VAMPIRE 6.0 or develop code. In the 2015 post seen at [6], a user found it to not work right for a hexagonal cell finding a workaround of translating the structure over to a cubic unit cell.  As far as I know, though, there has not yet been development of a code change to fix that.

[1] https://next-gen.materialsproject.org/materials/mp-21688/

[2] https://en.wikipedia.org/wiki/Hexagonal_crystal_family

[3] https://groups.google.com/g/vampire-users/c/dpC92netS4Q/m/d-35N6cRBgAJ

[4] https://groups.google.com/g/vampire-users/c/eqgl1iAWRpA/m/f4a_OJItAAAJ

[5] https://vampire.york.ac.uk/resources/vampire-manual.pdf

[6] https://groups.google.com/g/vampire-users/c/FsXzHbAgwcI/m/1vRZa-qvCwAJ

Kind Regards,

Gavin

VAMPIRE user