[Pw_forum] Modelling a 4-system high entropy alloy

[Zhao Y Leong]

Hi everyone,

Pardon the neophytic question(s) as I've just only started using QE.

I'm interested in modelling a four element based high entropy alloy to find
the energy band and fermi energy; according to the XRD tests I've done the
structure of the alloy is Cubic F3-M3 255 with a parameter of 3.57
angstroms.

I've tried using example_7 as a guideline but adding additional atoms into
a 255 group doesn't seem to work because the bravais symmetry gets
duplicated. Would it then be possible to input the elements into a a
triclinic system using coordinates of (0,0,0), (0.5,0.5,0),(0.5,0,0.5) and
(0,0.5,0.5) or is there another way to construct a 12 atom FCC unit cell
while randomising the atoms inside between the four alloys?

For now will be looking at using some ultrasoft pseudo-potentials. Will
that be fine and is it necessary to calculate the cut-off point for ecutwfc
as well or would it be fine to use a nominal value of lets say, 25?

Thank you,
Zhao
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