Charged systems of adsorption and desorption

[manoj_wijesingha]

Hi Colleagues,
I need to simulate and obtain the adsorption/desorption energies of the adsorbed Phosphates ions (PO4^-2) and desorption of decomposed organophosphates pesticides (eg: Chlorpyrifos) on the bulk surface or MOF. These systems have indicated the charges for example phosphates ions have -2 and decomposed organophosphates have -1 charged. To indicate the charge systems (3D system), I use NELECT and these tags, LMONO and EPSILON in this site (https://www.vasp.at/wiki/index.php/Cate ... trostatics). Are these key tags suitable to simulate and get right energies for these systems or are there any other process. I followed these as well (https://www.vasp.at/forum/viewtopic.php ... ECT#p31390, https://www.vasp.at/forum/viewtopic.php ... ECT#p31276, https://iopscience.iop.org/article/10.3 ... cd983/data). Could you please provide the suggestions.
Thank you.

Best Regards,
Manoj

[marie-therese.huebsch]

Dear Manoj,

I asked around a little but without much luck. The tags you mention are important in this context. However something to mind is that for VASP up to now, we do not have a way of constraining charge to a specific site. So whether the charge is added to the surface or the molecule is a matter of electronic minimization (with all its caveats regarding the XC functional correctly predicting the relative energy shift between molecular and bulk states).

I think that the forum from users for users may be a better place to get advice from other experienced users. Perhaps start a new topic there? I could also move this thread over, but in my experience threads that have a response already get less attention.

How do you want to proceed?