ABINIT Discussion Forums

Dear all,

I do need Your advice when it comes the to geometry-optimization of monoclinic lanthanoid chalcogenides. I‘m searching for transition-pressures between monoclinic and orthorhombic phases and found two ways how to get them using Abinit.

- Optimize atomic positions only, in a second run then optimize the positions again plus all the lattice parameters. One can:

1) Either give several volumes and calculate the total energies, to get E/V-curves for the different phases.

2) Use „strtarget“, to calculate total energies (and the corresp. V) for different pressures.

I think that for monoclinic cells it is not possible to use „strtarget“ due to its monoclinic angle and therefore 1) should be the only way to go, or am I missing something crucial?

I‘d be glad for any advice,
Christian

strtarget should work (remember that it's a 6-entry vector, using voigt notation) but you would have to be very careful to input the stress tensor such that it is consistent with the monoclinic space group. Bad things will happen if you input a strtarget that is incoherent with your input symmetry. Your other method of computation sounds much easier to do in practice.