Create two lattices in core-shell

[bipul.kum...@gmail.com]

Dear Vampire Users,

                                 I was trying to create a core-shell particle using Co and NiFe. Cobalt is HCP while NiFe is FCC and the lattice parameters are different.

Q.1. How can I create two different lattices in the input file ?

As far I know, we can not include two .ucf files.

Thanks in advance,

Regards,

Bipul

[gabo...@gmail.com]

Someone else may know differently.  Unfortunately, that does not currently look easy to do.

One approach might be to use C++ programming to make your own custom crystal structure for that.  If you look in the unitcell folder [1] of the VAMPIRE 6.0, it looks like it contains the files for the built-in structures such as sc (sc.cpp), bcc (bcc.cpp), etc.

A second approach might be to transform each of the HCP and FCC into a common primitive unit cell (space group P1) and then combine them together to create a P1 supercell structure, since any of the space groups can be defined in P1 [2].  P1, however, is triclinic [3] with non-orthogonal lattice angles and not one of the crystal structures listed as being supported by VAMPIRE at [4].  The challenge impeding implementation of non-orthogonal unit cells is described at [5,6].  Core shell systems can be done with a single ucf file [7] but you would need to be able to map the HCP/FCC (or P1 supercell structure of them) to a primitive cubic lattice [8] (or create:crystal-structure = sc [4]) as mentioned at [9].

[1] https://github.com/richard-evans/vampire/tree/v6.0/src/unitcell

[2] http://pd.chem.ucl.ac.uk/pdnn/symm3/sgtricl.htm

[3] https://en.wikipedia.org/wiki/Triclinic_crystal_system

[4] https://vampire.york.ac.uk/tutorials/system-generation/crystal-structure/

[5] https://groups.google.com/g/vampire-users/c/PGccY_rsRBI/m/CtDCZLRowz4J

[6] https://groups.google.com/g/vampire-users/c/bL_LH6GncMo/m/b5W22mMqBgAJ

[7] https://groups.google.com/g/vampire-users/c/QGFtYVB6Kd8/m/aJLRijgZBQAJ

[8] https://en.wikipedia.org/wiki/Cubic_crystal_system

[9] https://groups.google.com/g/vampire-users/c/ubgiSq3X9AY/m/PgNtvEnECQAJ

Kind Regards,

Gavin

VAMPIRE user