Hello all,
I am still having a problem with relaxing a structure (hexagonal).. The initial
pressure was calculated to be -12 kbars. I managed to reduce the pressure to
0.02 and the total force to 0.0007 using vc-relax. However when I ran a scf
calculation on the relaxed structure , the pressure was again -16 and the total
force 0.4. Professor Paolo G. gave me a link for this problem.. I understood
that I need to increase the cutoff kinteic energy which I did and I realized
that the pressure goes down but to -6; however the total force is still 0.4!
(1) Anyone knows how to solve this problem.
I have run the calculation again wih ibrav=0 instead of ibrav=6 and the crystal
axes were:
a(1) = ( 0.492694 0.853319 0.000001 ) a(2)
= ( 0.492685 -0.853314 -0.000001 ) a(3) = ( 0.000001
0.000004 4.274389 )
The pressure was -0.02 and the total force was 0.001 which was fine in both scf
and vc-relax. However when I redid an scf calculation with ibrav=6 with c/a
=4.274389 (which I read from the ibrav=0 calculation with the same atomic
positions of the "ibrav=0" calculation), I still got P =-16 and total
force=0.4. I was trying to convert the ibrav=0 input to ibrav=6..did I do
anything wrong?
Any help would be appreciated
Thanks
Elio Nahdan
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