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Hello Malcolm,

I am using version

I am relieved you reproduced my observation. I was starting to think that I must be getting a bit soft in the head.

Enjoy your summer break,

Since I was using a slightly older version of Mathematica (10.3) I decided to update to 10.4 and try again.

This time I got the same behaviour as you!

So there is a subtle difference between Mathematica 10.3 and 10.4 which causes different behaviour for this particular calculation, which is very unexpected. I hope to debug this after my summer break.

There should be no need for you to send me the files I requested in the previous post.

all the best
Publications / LLS relaxation in CH2D groups
« Last post by sje1g13 on July 27, 2016, 09:23:14 AM »
The paper:

Stuart J. Elliott, Lynda J. Brown, Jean-Nicolas Dumez & Malcolm H. Levitt, Phys. Chem. Chem. Phys., 18, 17965-17972 (2016)

uses SpinDynamica to treat the relaxation of long-lived singlet order in monodeuterated methyl groups and uses an effective CH2D geometry to explain experimentally observed results.

A link to the relevant notebook will follow shortly.
Thanks Andy,
 this is very puzzling. Which version of Mathematica do you have?

 Can you run the attached file on your system including the Trace instructions and send the result back. If its too large to attach here please put it on dropbox and send me the link, or some other way. I want to see the complete file, not just screen clips.

 please start from a completely clean kernel and simply add a $Path instruction before Needs, if you need to do that.

 I will be away for a while now but I will look at this in the course of time. I havent seen a case where the same code gives different results when running the same version of Mathematica and SpinDynamica on separate systems.

Hello Malcolm,

Thank you for getting back to me on this question (and my chemical exchange question on a separate post).

I just did as you suggested, and attached a screenshot of the outcome. I started up the Mathematica program and typed the example from scratch into a new notebook.

I even re-downloaded your latest version of SpinDynamica.

Hi Andy, thanks for posting - I just checked the forum and picked up on your problem.

This puzzles me since when I add the line Needs["SpinDynamica`"] to the top of your file and run it, starting from a clean kernel, I do not get the behaviour you describe (see attached file). One possibility is that you were trying out some of the features in the documentation, such as the setting for $Chronology (end of part 1) and that a setting was thereby changed. Mathematica has the feature that anything you do in a session persists for the rest of the session, so maybe that is the problem.

Please retry, starting from a clean kernel (i.e. restart the kernel) and using the Needs line above to load SpinDynamica. Let me know how it goes.

All the best
Publications / Re: Spatial Frequency Encoding NMR
« Last post by MalcolmHLevitt on July 26, 2016, 04:44:20 PM »
thanks for posting!

ps. any chance of posting the notebook on this forum as an attachment (perhaps with graphics stripped out to save space)?
Publications / Spatial Frequency Encoding NMR
« Last post by Nicolas Giraud on July 22, 2016, 09:53:30 AM »
Our recent paper :

Achieving high resolution and optimizing sensitivity in spatial frequency encoding NMR spectroscopy: from theory to practice
by Bertrand Plainchont, Daisy Pitoux, Ghanem Hamdoun, Jean-Michel Ouvrard, Denis Merlet, Jonathan Farjon and Nicolas Giraud
Phys. Chem. Chem. Phys., 2016 (

uses SpinDynamica to simulate a spatial frequency encoding (SFE) process induced by the use of gradient encoded selective pulses. Notably, we have written a notebook to simulate J-edited spectra obtained in a 2D G-SERF experiment. This notebook is available upon request.
Examples / Re: Chemical exchange in an AB system
« Last post by MalcolmHLevitt on July 18, 2016, 01:44:18 PM »
Hi Andy,
 thanks for this. Just as for the AB case I posted, handling chemical exchange (as required for CPMG on a chemically exchanging system) entirely within SpinDynamica is currently not possible, although the necessary package extension is thoroughly feasible and the necessary functionality has long been planned. The problem is time and manpower. The existence of a strong demand is a very good stimulus but I am simply too busy to promise it in a short timeframe. If anyone is out there who feels sufficiently motivated to take on a programming task of this kind, I am very willing to help them.
 So although a general implementation of multisite chemical exchange in SpinDynamica is still some way off, programming a task-specific piece of code (as I did for the AB example) is more feasible. However, once again, my lack of time makes it hard to do this without additional help.
 sorry for this discouraging news
Examples / Re: Chemical exchange in an AB system
« Last post by aliwang on July 16, 2016, 04:39:06 PM »
Dear Malcolm,

Is there a way to adapt this module so that chemical exchange can be studied using Trajectory? It would be fantastic if we could use SpinDynamica to simulate CPMG pulse trains as a function of RF power on systems undergoing a range of chemical exchange regimes.

My best respects,
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