[Pw_forum] enthalpy of adsorbtion of o2 molecule on a ZnO supercell

[Prasenjit Ghosh]

Dear Meysam,

In principle they are different quantities. Generally enthalpy (H) is
related to the internal energy (E) as H=E+PV (P=pressure
V=volume)....so change in enthalpy upon adsorption of a molecule
(enthalpy of adsorption) is given by

dH=dE+PdV+VdP

where dE is the adsorption energy for your case (and is -ve if the
molecule binds).

Now if you consider your system to be the surface with molecule
adsorbed on it, then for a given coverage, the volume & pressure is
constant.....so in that case dH=-dE, i.e. the enthalpy of adsorption
is -(adsorption energy)

Prasenjit

On 15 October 2010 14:18, meysam pazoki <m_pazoki at physics.sharif.edu> wrote:
> Dear mohnish and Prasenjit
>
> Thanks  for your good answers ,I have another question :"Is enthalpy of
> adsorbtion equals to energy of adsorbtion?"
> I want to calculate enthalpy of adsorbtion and your answers are about energy
> of adsorbtion.
>
> Regards
> Meysam Pazoki
> SUT
>
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>



-- 
PRASENJIT GHOSH,
Assistant Professor,
IISER Pune,
First floor, Central Tower, Sai Trinity Building
Garware Circle, Sutarwadi, Pashan
Pune, Maharashtra 411021, India

Phone: +91 (20) 2590 8203
Fax: +91 (20) 2589 9790