[Pw_forum] A QUESTION about the precision of relaxation

[xu yuehua]

hi everyone ,
i am now do a relax job.my uint cell is a supercell . and i only want to
relax a direction of lattice ,for example c .
so i tried to vary the c .and compute. see the stress.but i do not know how
to adjust the c on the base of the result like:

 entering subroutine stress ...

          total   stress  (Ry/bohr**3)                   (kbar)     P=   -
1.06
  -0.00000893  -0.00000001  -0.00000001         -1.31      0.00      0.00
  -0.00000001  -0.00000892   0.00000000          0.00     -1.31      0.00
  -0.00000001   0.00000000  -0.00000382          0.00      0.00     -0.56


(10there is "-0.56" and the "-" stands for .i should  the reduce c?

 (2)0.56 is a large stres?

(3) is there any other way to determine the suitable c?

thank you very much if you could give a advice .

bests


-- 
Xu Yuehua
physics Department of Nanjing university
China
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