Independent from my general kinetics question here - Estimating Surface Reactions - Liquid, Turbulent Flow - I am only interested in responses regarding Gaussian in this question.

I would like to know if it is feasible to predict or model the influence of a surface (metal) on a reaction between two hydrocarbons (aromatic and aldehyde for example) in Gaussian. If yes, how would I go about it? (Building a small metal grid and working with it is very computationally intensive - it is the only approach I can think off...)

(I have access to Gaussian at my university - however I do not have access to Linda, so no shared nodes.)

  • $\begingroup$ I'm no expert with surface chemistry and I avoid metals like the plague. I do use G09 on a daily basis so I'm only speaking from the other side of the fence here but... you may be interested in something like ADF (Amsterdam Density Functional). Also, I think NWChem may be something to look into as well. Its freely available unlike ADF. $\endgroup$ – LordStryker May 20 '13 at 15:03
  • $\begingroup$ I doubt my university wants to buy anything - but I came across NWChem once before... but never looked at it in greater detail. Maybe I should - also metal surface effects have only become a focus because they are the only explanation for the reactions I am looking at (liquid phase is what we initially though but Gaussian suggests no...). Thanks. $\endgroup$ – DetlevCM May 20 '13 at 17:27
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    $\begingroup$ Well, do yourself a favor and find an alternative to Gaussian. There are options out there that will be much more efficient and better suited to modeling metals and surfaces. $\endgroup$ – LordStryker May 20 '13 at 19:29
  • $\begingroup$ @LordStryker That is one option - though there is always the issue of support. Heck, I even ended up with chemistry coming from mathematics and originally planning to do CFD - my topic has lead me into chemistry... $\endgroup$ – DetlevCM May 21 '13 at 8:32
  • $\begingroup$ I would strongly recommend you to check out Matter Modeling SE where you find people more experienced in this subject (no offense to Chemistry SE). Also, surface catalytic modeling takes a lot of experience, so it might not be the best as your first project. If you do not insist Gaussian (not recommended tool), you can use free or open-source software (Quantum Espresso, CASTEP, etc) $\endgroup$ – Greg Jul 8 at 8:04

You did go to Gaussian's Documentation on the subject, right?

In principle, it should work. In practice, you should consider using massive firepower, and the plane-wave codes (NWChem, abinit, VASP, etc. etc.)

Also, I question whether any of these codes properly model bond breaking on a surface, i.e. metal-catalyzed reactions. Big simulations don't guarantee correct wave functions.

I should point out that surface reactions with plane waves are also difficult. At least they used to be. There are/were issues with Ewald summation having to be done in 3D, and so the surface normal dimension used to have to be HUGE to avoid image effects.

This is a tough business.

  • $\begingroup$ Thank you for pointing me at this, however I cannot quite see how I can use that. All this tells me is "an option exists"... - Maybe I need to dig around this... (I will also be attending the Gaussian course in Wroclaw in June) Having said that - when you mention "massive firepower" I suspect I might run into trouble with my university's cluster - I do not have Linda available and the biggest node I can use is 12 cores and 24GB of RAM... (More cores = more nodes, therefore no Gaussian for me) $\endgroup$ – DetlevCM May 21 '13 at 8:35
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    $\begingroup$ If you google: Gaussian PBC examples, you get this page: scuseria.rice.edu/gau/gdv_pbc/pbc_guide.html $\endgroup$ – Eric Brown May 21 '13 at 12:40
  • $\begingroup$ That is a start - lots of fun - I will have a read of it and try to understand as much as possible (Maths background). I was also thinking of trying to get NWChem to run on our computing cluster - being free that should be doable. For now I gave you a +1 on your answer. $\endgroup$ – DetlevCM May 21 '13 at 12:46

Well, I am sure you found the answer (it's been 4 years since you asked the question), but you can use VASP (the Vienna Ab-Initio Simulation Package) or if you don't have or can't afford a licence for VASP, then Quantum Espresso is great too (though it's a pain to get a hang of if you are teaching it to yourself). Also, Schrodinger now comes enabled with Quantum Espresso plane wave code for solid state chemistry calculations.

  • $\begingroup$ NWChem is another option for plane waves that I did briefly use - but never went beyond testing (with the resources at the time). But even with a plane wave code, the problem is non-trivial due to the cell size. (Should be a lot better with the computers of today, but I moved on to other details of the same science area.) $\endgroup$ – DetlevCM Jun 2 '17 at 17:20

I have done some work with reactions on organic surfaces, and hybrid QM/MM calculations helped me solve my problem, particularly using the ONIOM forcefield. I understand that a classical forcefield may not be the best way to treat a metal surface, however.

  • $\begingroup$ I actually gave up on that avenue eventually - due to a lack of computational resources. In principle, ONIOM is an option. A colleague suggested freezing bonds which is another option. (But introduces its own issues.) $\endgroup$ – DetlevCM Jan 20 '15 at 10:10

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