[Pw_forum] How to relax the HCP type structures?

[Yi Kong]

Dear All,
    I want to find the ground state of D019 (HCP type) structure of
Pd-Ru alloys in the PWSCF, I follow the input of the EXAMPLE 3, and
the structure parameters I input are:
*********************************************
  ibrav= 4, celldm(1)= $acons,celldm(3)=$ccons,  nat=8, ntyp=2,
 ...
 ...
 ATOMIC_POSITIONS (crystal)
 Ru  0.50          0.0            0.00  
 Ru  0.50          0.50          0.00
 Ru  0.00          0.50          0.00 
 Ru  0.333333   0.1666667 0.50 
 Ru  0.833333   0.1666667 0.50 
 Ru  0.833333   0.6666667 0.50 
 Pd  0.00          0.00          0.00 
 Pd  0.333333   0.6666667 0.50 
************************************************
    The $acons and $ccons are varied so as to find the lattice
constants a and c through comparing the obtained energies.

I just want to know that are these input correct, and are there more
efficient method to find the ground state of the HCP type structures.

Thanks a lot!

-- 
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Yi Kong
Department of MSE
Tsinghua University
PR China, 100084
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