[Pw_forum] volume in output file.

[Mighfar Imam]

Dear Jiayu,
The lattice vectors of a fcc crystal are taken
as a_1=a/2(i+j) etc. So the volume |a_1.(a_2 x
a_3)|
will turn out to be 1/4(a^3) rather than a^3.

-Mighfar Imam
JNCASR,
B'lore, India.

> Dear all users,
>
> When i performed the vc-relax calculation, i
> found the "unit-cell volume" in the
> output file is not the volume of the supercell i
> used. I also found it is the same
> in the SCF calculation. For example, in SCF
> calculation, my input lattice ibrav =2
> (.ie., fcc), celldm(1)=10.6920, then the output
> parameters are:
>
> lattice parameter (a_0)   =      10.6920  a.u.
> -------a
> unit-cell volume          =     305.5743
> -------omega
>
> You can see omega is not the cubic of a. Then,
> how the volume "omega" in the code
> is calculated here? Is it included in the
> cell_base.f90 file?
>
> Thanks a lot.
>
> Jiayu
>
>
>
>
> ------------------------------
> -------------------------------------------
> Jiayu Dai
> Department of Physics
> National University of Defense Technology,
> Changsha, 410073, P R China
> -----------------------------------------
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