Subject: Summary: Silver NMR shifts using PBC

From: leif.olson~at~kodak.com
Date: Fri, 21 Jan 2005 11:33:52 -0500

Hello CCL, 

I received several replies to my question from January 12th, about 
computing
Ag-109 chemical shifts of a crystal, using periodic boundary conditions. 
The 
purpose of this is to compare the results to a CP-MAS solid-state NMR 
spectrum.

Thanks to Stan van Gisbergen (SCM), George Fitzgerald (Accelrys), Alex
Hofmann (Humboldt-Universitaet Berlin), and Georg Schreckenbach
(U. of Manitoba) for their assistance.  Their slightly edited replies are 
pasted 
at bottom.

It seems PARATEC, CPMD, and NMR-CASTEP can do NMR shifts using PBC. 
Maybe other programs do too, but those are the ones I now know about. 
Alex suggested that with CPMD, wavefunction convergence with metals 
could be difficult. 

Although ADF does not seem to have NMR capability using PBC yet, Georg
and his research group are working on this now, based on the ADF-BAND 
code.

Meanwhile I am weighing options, including the idea of cluster vs. PBC.

Leif Olson
Eastman Kodak Research Laboratories

P.S. about using ECPs on metal atoms...though I have not done a lot of 
basis set testing, I have found that for Ag, the DFT-optimized DZVP
(sometimes called "DZVP2", I think?) basis set of Godbout et al. works 
well 
in many situations where an all-electron basis set is needed.

*****

Dear Dr. Olson,

I hope the following commercial information is relevant to your 
question.

Our Amsterdam Density Functional (ADF) program is very well suited for 
calculating NMR parameters
of molecules and clusters [both spin-spin coupling and chemical shifts].
Relativistic effects [scalar and spin-orbit] can be taken into account 
if needed.
All-electron NMR calculations are no problem. The NMR code runs in 
parallel, so large clusters can
be handled with ease.

This has been successfully applied to solid-state NMR as well because a 
[large] cluster description is often
sufficient.

We can offer you a free trial for ADF if you would like to see how it 
works for your system(s).
I could also send you some NMR references related to ADF and/or the 
general ADF brochure,
and/or provide further details by phone [also on recent developments 
for solid-state NMR
in our periodic structure program BAND], all upon your request.

Best regards,
Stan van Gisbergen

*****

Dear Leif, 

Accelrys offers the program NMR CASTEP  for computing NMR chemical shifts 
and 
electric field gradient tensors for solid-state systems. You can find more 
information on our web site at http://www.accelrys.com/mstudio/ms_modeling/nmrcastep.html. The underlying method is similar to that implemented in PARATEC. The 
CASTEP interface, however, makes the implementation very easy to use. 

I will contact you privately with additional information. 

Sincerley, 
George Fitzgerald

*****

Hi Leif,

I think CPMD is in that sense not better than many other plane wave codes. 
Especially it might be tricke to get wavefunction convergency with metals 
in CPMD. For this you may consult experts like Ari Seitsonen or somebody 
connected to the CPMD-group.

Another way may be to cut part of the crystal as (highly symmetric) 
cluster and do that with Gaussian or Turbomole.

Hth

Alex

*****

Dear Leif,

Briefly, we are also working on the very subject (to create such a 
method, that is), and we hope to have a running code (based on 
ADF-BAND) in about a year -- although I might be optimistic.

As to your questions: 1. Gaussian cannot do it at the moment, as you 
have found out.
2. If you find a code that can do it, you need to be a bit careful 
because:
- to get the metal NMR chemical shift right, you don't normally want a 
pseudopotential (ECP) at that very atom. Some workarounds have been 
discussed in the lit. but I am not sure about the latest details.
- on the other hand, you probably need a relativistic description of 
your system, although you MIGHT just barely get by without for a second 
transition row atom.

Best regards, Georg

*****