ABINIT Discussion Forums

hello,
I want to add hydrostatic pressure to a system, but i don't know how to solve it?
I mean I have no conception between "strtarget" and hydrostatic, also the "optcell" and "ionmov"

sincerely,
Lichun

Well, strtarget is the desired final stress generated by the cell, in Voigt notation. So the longitudinal components are the first three entries and the shear components are the second three. The units are atomic, that is, Hartree/Bohr^3. So 1 GPa = 3.40E-5 in atomic units. So if you want the final structure to be under an external hydrostatic pressure of 1 GPa, set strtarget to -3.4E-5 -3.4E-5 -3.4E-5 0.0 0.0 0.0. If you want a negative external pressure (tension) change the signs to positive (remember that strtarget refers to internal stress). In order for this variable to do anything you will have to be relaxing the cell with ionmov 2 and optcell 1 or optcell 2.