[Wien] two questions about NMR calculations

Bing Zhou luxunca at yahoo.ca
Mon Oct 28 08:30:58 CET 2013

Dear Robert,

It is so great to have the response from you, I have carefully read your series publications about NMR chemical shift calculations using WIEN2k on Physical Review B, which are so helpful.

Using the borate mineral of probatite (CaNa[B5O7(OH)4].3H20) as an example, I am going to investigate the magnetic shielding mechanism at the five B sites in it by decomposing the chemical shifts into different energy windows. These energy windows include core states (<-3.6), Na/2s (-3.6, -3.5), Ca/3s (-2.8, -2.6), Na/2p (-1.5, -1.45), Ca/3p & O/2s (-1.45, -1.1), B/2s (-0.7, -0.45), B/2p & Na/3s, Ca/43 and O/2p (>-0.45). Of course, I also calculated the contributions from the energy window gaps between them, which usually are very close to 0.0000.

At the same time, I also obtained the chemical shifts (":NMRTOTxxx) at each B sites from the energy window of (-infinity, +infinity) by running "x_nmr_lapw".

I tabulated the data of ":NMRTOTxxx" from the above different energy windows using "x_nmr_lapw -emin xx -emax yy". However, the ":NMRTOTxxx" from (-infinity, +infinity) is not equal the summation of ":NMRTOTxxx" from the above windows such as core states, Na/2p, B/2s, O/2p, B/2p etc. There exists a systematic differenece around 11 ppm between the summation and that for (-infinity, +infinity), may I interpret such a difference as the interestial contributions for the chemical shifts?

On the other hand, the summations of ":NMRTOTxxx" from the above energy windows also deviate from the corresponding summations of ":NMRSPHxxx" as expected, may I also explain such deviations as from the interestial contributions?

In one word, I am a begainner for such a NMR study, I am desperate for your helps, I hope you don't mind giving me further helps when you are available.

Thank you again!


On Sun, 10/27/13, Robert Laskowski <rolask at ihpc.a-star.edu.sg> wrote:

 Subject: Re: [Wien] two questions about NMR calculations
 To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at>
 Received: Sunday, October 27, 2013, 8:49 PM
 energy is in Ry. Did you included core contribution to the
 total shielding?
 It is excluded when emin is specified.
 On 28 October 2013 AM 8:25:37 Bing Zhou wrote:
 > Dear all,
 > I try to decompose the magnetic shielding contributions
 into different
 > energy windows using DOS, here I have two questions in
 > "x_nmr_lapw":
 > Question 1 is about the additivity of the NMR shielding
 contributions from
 > different energy windows: I assume the summation for
 the shielding
 > contributions from each energy windows should be equal
 to the total
 > chemical shielding calculated. However, it seems not
 that case, i.e., the
 > summation did not add up to the total shielding
 calculated, am I right or
 > did I miss something?
 > Questions 2 is simply about the energy unit used for
 energy window of DOS:
 > there are two energy units (eV and Ry) for DOS map,
 however, what is the
 > default energy unit in running "x_nmr_lapw -emin xx
 -emax yy"? "xx" and
 > "yy" are in the unit of Ry?
 > Thank you in advance!
 > Bing
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 Dr. Robert Laskowski
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 Institute of High Performance Computing, A*STAR
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