So I am thinking I want to do vc-relax allowing A,B,C to vary in Base-centered orthorhombic while keeping the volume fixed.
I know we can do cell_dofree in the pw.x input file and can modify cell_base.f90 if an option that we want isn't available to us. The issue I'm having is that we can do in cell_base.f90 I'll keep the cell volume fixed and vary the vectors of the primitive ORCC cell as so.. 1 1 0 1 1 0 0 0 1 with fix_volume=.true. but if I use that iforceh with fix_volume then I will get cell_parameters that will vary like this: (CP11 , CP12 , 0, ), (CP11 , CP12 , 0, ), (0 , 0 , CP33,), CP11 != CP12 and CP21 != CP22 so I am thinking I am losing the ORCC primitive cell shape. Ideally I'd like to make it so CP11 == CP12 and CP21 == CP22 while varying CP11,CP22, and CP33 and keeping a constant volume. One option would be to transform the primitive ORCC cell and atomic_positions to it's conventional counterpart and do cell_dofree='xyz' with adding fix_volume=.true. to cell_base.f90. I'd rather not do that just because it would take a while to do a vc-relax with 90 atoms (and I'm thinking I want to do this for a few dozen chemical variations of the same system) Any suggestions? Thanks, Andrew
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