Additive QM/MM setup

[Dave McKay]

Dear all,

A few of us from my group attended the CP2K course in London in the Autumn and were particularly interested in the dissociation free energy exercise (http://www.cp2k.org/exercises:2014_ethz_mmm:index - Lecture 13).  We have since repeated this and also done the gas phase part with DFT-D3 (BP86 and PBE).

We are now interested in combining our DFT input with the FIST input from the lecture in an additive QM/MM scheme (we want to use the additive scheme because we'd like to move on to anions for which we have no MM parameters).

In the notes we received there was a description of the input for a subtractive QM/MM and also theoretical background for electrostatic embedding and an intro to GEEP.  However I can't find an example of how to run this.  I've taken some pointers from the example here: http://www.cp2k.org/exercises:2014_uzh_molsim:chp_cu111

My input as it stands is attached - I think the sections I have so far are OK(?) but I also think there are sections missing (QMMM? GEEP?).

I'd be grateful for any pointers.

Thanks,

Dave

[Teodoro Laino]

Dave,

1) Strictly speaking the "QM/MM" scheme implemented in CP2K is additive only: E_tot=E_QM+E_MM+E_QMMM(QM-MM)

2) subtractive schemes: E_tot=E_MM(QM+MM)+E_QM-E_MM(MM), can be done with cp2k too, but they are worldwide known as ONIOM models (rather than QM/MM). Unfortunately, the title of the exercise you referred to, is at least misleading and has not really too much to do with QM/MM. As you guessed there will be many missing sections if you take this as an example for building your own QM/MM input.

3) there were on the portal - somewhere, not sure where though - the exercises we did in the last tutorial in Zurich (you may want to check with the webmaster for their precise location). We had 3 “real” QM/MM input files there, which may help you.

3) your input is - unfortunately - not attached

a good starting point for the theory is in the two papers describing the QM/MM coupling in cp2k. Feel free to ask for any question.

rgds,

Teo

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[Dave McKay]

Hi Teo,

Thanks for the info and for the clarification on the meaning of 'additive qm/mm'.  I'm going to have a look at the test files, do some reading and hunt around for the tutorials you suggest.

Yes, I realised I hadn't attached my input an hour or so after posting... You must have beaten me to it.

Thanks anyway and I'll no doubt come back with questions in the future.

Dave

[max mercy]

Hi Dave,

Have you found the internet link for the exercises QM/MM as Teo suggest?

Can you share it?

Thanks

Maxime

[Dave McKay]

Hi Maxime,

The 2011 workshop on qm/mm is here: http://www.cecam.org/workshop-4-515.html

where you can find all the lectures.

It looks like the workshop that's been advertised in the Google groups site and is on here: http://www.cp2k.org/events/

I have to admit I haven't tried it yet, so I don't know if the page has exactly what I was looking for, but it's on my to-do list!

Joyeux Noel!

Dave

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