[Pw_forum] How to add air pressure on adsorption calculation using Pwscf

[Oliviero Andreussi]

Well, as a matter of fact you could try to use the quantum-enthalpy 
functional of Matteo Cococcioni et al. Phys. Rev. Lett. *94*, 145501

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.94.145501

Please double check that this is something that may be useful for your 
calculations. In case, the method is implemented in the CP code, 
PRESS_AI namelist, but also in PW by exploiting the external Environ 
module (which you would need to download and compile, more details can 
be found here www.quantum-environment.org). The actual release of 
Environ is compatible with QE 5.1, 5.1.1 and 5.1.2, if you are using a 
more recent version I could let you have the patch.

Oliviero Andreussi

Senior Postdoctoral Researcher

École Polytechnique Fédérale de Lausanne (EPFL) and

Università della Svizzera Italiana (USI) of Lugano

Switzerland




On 10/28/2015 10:05 AM, Lorenzo Paulatto wrote:
> On Wednesday, October 28, 2015 04:13:41 PM 李睿 wrote:
>> Hello, everyone
>> I want to calculate molecules adsorption under 1Bar air pressure using
>> Pwscf. Can I add air pressure in it?
> No, you cannot. Gas pressure is a macroscopic variable. It does not exist in a
> zero-temperature DFT calculation. You may do a molecular dynamics simulation
> with a bunch of molecules at a certain temperature, but it is very impractical
> and deducing the pressure from volume+temperature when the volume is so small
> and includes a chemically reactive surface is not granted.
>
> What you can do is to include its effect via a chemical potential, you can
> find a brief explanation in chapter 3.2 of my PhD thesis
> <http://urania.sissa.it/xmlui/bitstream/handle/1963/5363/paulatto_thesis.pdf?sequence=1&isAllowed=y>
> (eq. 3.12 in particular, but read all the chapter). If I remember correctly, I
> studied the problem on  "Arthur W. Adamson, Physical Chemistry of Surfaces,
> John Wiley and Sons, 1990", so if you can get a copy of the book you'll find a
> better and longer explanation.
>
> HTH
>

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