[Pw_forum] calculate equation of state in Quantum Espresso

[Layla Martin-Samos]

Yes you have to calculate the total energy for different lattice
parameters. 1) and 2) yes, E-V is a parabola where the min is the
equilibrium lattice parameters is always better to have points on both
sides. 3) only relax as if you relax the cell you will always fall into the
min.

cheers

Layla

2012/10/24 David Furman <sirok4 at gmail.com>

> Dear all,****
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> I want to calculate equation of state (E-V curve) with Quantum Espresso.**
> **
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> What is the procedure to do so ? ****
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> I think to calculate the total energy of different lattice parameters and
> then fit to analytic equation of state.****
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> 1. Do I additionally to compressing (setting smaller and smaller values
> for lattice parameter) need to calculate energy for lattice parameters
> larger than equilibrium ? ****
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> 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 ?****
>
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> 3. Do I have to do relax or vc-relax runs to optimize atomic positions at
> each lattice parameter ?****
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> Thanks for you kind help,****
>
> ** **
>
> ** **
>
> David****
>
> ** **
>
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