[Pw_forum] calculate equation of state in Quantum Espresso

[David Furman]

Dear all,

 

I want to calculate equation of state (E-V curve) with Quantum Espresso.

What is the procedure to do so ? 

 

I think to calculate the total energy of different lattice parameters and
then fit to analytic equation of state.

 

1. Do I additionally to compressing (setting smaller and smaller values for
lattice parameter) need to calculate energy for lattice parameters larger
than equilibrium ? 

 

2. If yes, then what sense does expanding the unit cell mean regarding to
experiment ? 

     Or is it done just to improve the statistics of the fit ?

 

3. Do I have to do relax or vc-relax runs to optimize atomic positions at
each lattice parameter ?

 

Thanks for you kind help,

 

 

David

 

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