The ABINIT Users Mailing List ( CLOSED )

[wlu7910@126.com]

Dear all,
   I am a newer to ABINT. I want to ask if the pressure given in the *.out 
file is equal to (-stress)?
   Another question is that I want to calculate the shear stress for a series 
of strains along the direction eg. (111)<1 -1 0>. But I don't know how to add 
this kind strain to the primitive vector (for example fcc). what I know now 
is to redefine the structure of the original fcc structure (cleave plane 
(111) with surface vector [0.5 -0.5 0] and [0.5 0.5 -1], and the third 
direction is perpendictular with (111)), then add small strain to the third 
direction along [0.5 -0.5 0] direction. Now I meet a problem, If I can use 
the conventional cell to get the stress of the distorted structure in ABINIT?
   I use the tutorial structure of Al (still keep fcc structure without 
distortion)with lattice constant 7.8 bohr (do not optimization)to test the 
stress in primitive cell and conventional cell, respectively. The result of 
these pressures are [Pressure= -5.6996E+00 GPa] and [Pressure= -6.9105E+00 
GPa] (ecut=20 H and shiftk is same for the two tests). So what's the 
relationship of the pressure calcuated in primitive cell and conventional 
cell?
  
   Thank you very much for your help!
 
Best Regards,
   WLu