[Pw_forum] Calculation of orthorhombic lattice parameters from the basis vecotrs

[yedu kondalu]

Dear users,

     I did the structural optimization of a compound belongs to the space
group *Ibam-72* (body centred orthorhombic) using variable cell  (vc-relax)
method.

     lattice parameter (alat)  =      10.5862  a.u.
     unit-cell volume             =     675.9126 (a.u.)^3

The initial basis vectors
               a(1) = (   0.500000   0.529989   0.537487 )
               a(2) = (  -0.500000   0.529989   0.537487 )
               a(3) = (  -0.500000  -0.529989   0.537487 )

After the structural optimization the vectors are

  new unit-cell volume =    614.83507 a.u.^3 (    91.10916 Ang^3 )

  CELL_PARAMETERS (alat= 10.58624499)
   0.529016060   0.479936985   0.510293152
  -0.529016060   0.479936985   0.510293152
  -0.529016060  -0.479936985   0.510293152

1.  How to calculate the lattice parameters  for this case ?

2. How to do the same for all the non cubic systems ?

Can some body please explain me any method or reference books to do the
same ?


Thanking you

Regards
KONDAL
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