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Topics - MalcolmHLevitt

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Examples / Spin-3/2 dynamics
« on: January 16, 2015, 04:07:33 PM »
A new example file has been posted on
The example file illustrates the spin dynamics of a spin-3/2 system in the presence of weak and strong rf fields. Selective manipulations of the central and satellite transitions are illustrated, including the use of cosine-modulated fields to excite the satellite transitions.

Updates and Messages / SpinDynamica 2.11.1
« on: December 08, 2014, 02:03:49 PM »
SpinDynamica 2.11.1 has been released here:

This is a relatively major new release with new functions ProductKet, ProductBra and ProductBasis. See part 3 of the documentation.

Signal1D has been augmented with new functionality allowing direct specification of the number of sampling points and the spectral width. See part 2 of the documentation.

Major speed improvements have been achieved for some calculations.
A variety of minor bugs have been fixed.

Updates and Messages / SpinDynamica 2.10.2 released
« on: September 24, 2014, 10:16:49 PM »
SpinDynamica 2.10.2 is now available here:

This corrects some nasty misbehaviour which appeared in 2.10.1.

Examples / Quadrupolar echoes for spin-7/2
« on: September 19, 2014, 06:12:33 PM »
The attached notebook shows how to calculate the spectrum of a spin-7/2 nucleus (for example 133Cs) in an oriented medium, such as a gel (see for example P. W. Kuchel, "Quadrupolar Splitting in Stretched Hydrogels," in "eMagRes," Ed. (John Wiley & Sons, Ltd, 2007)). The EnsembleAverage function is used to generated a spread in quadrupolar interactions, corresponding to gel inhomogeneity. A simulation shows that a two-pulse sequence generates a series of quadrupolar echoes with curious fractional timings, as predicted in a very old paper by Solomon (I. Solomon, "Multiple Echoes in Solids," Phys. Rev. 110, 61 (1958)).

Examples / Chemical exchange in an AB system
« on: September 19, 2014, 06:07:01 PM »
The attached notebook shows how to build on SpinDynamica to predict the NMR spectrum of an AB system of two spins-1/2, exchanging between two sites with different chemical shifts and J-couplings. Currently, this case cannot be simulated entirely within SpinDynamica, but the notebook shows how to build on SpinDynamica so as to handle a chemical exchange case. Thanks to Phil Kuchel for stimulating this simulation. Malcolm

ps. I have stripped the graphics from the attached notebook but they will be regenerated when the code is executed.

Updates and Messages / SpinDynamica 2.10.1
« on: August 11, 2014, 04:29:05 PM »
SpinDynamica 2.10.1 has been released. More bug fixes and speed enhancements. Download here:

Updates and Messages / SpinDynamica 2.9.1 released.
« on: April 06, 2014, 10:41:57 PM »
SpinDynamica 2.9.1 has been released.

The release contains the full SpinDynamica code and executable documentation notebooks.

Enhancements with respect to SDv2.8.3:
  • Compatibility with Mathematica 9.
  • Bug fixes.

Updates and Messages / SpinDynamica 2.8.3 released
« on: November 19, 2013, 03:37:42 PM »
SpinDynamica 2.8.2 has been released.

The release contains the full SpinDynamica code and executable documentation notebooks.

Enhancements with respect to SDv2.8.2:

        Important bug fixes.

Updates and Messages / SpinDynamica 2.8.2
« on: October 13, 2013, 06:12:04 PM »
SpinDynamica 2.8.2 has been released.

The release contains the full SpinDynamica code and executable documentation notebooks.

Enhancements with respect to SDv2.8.1:
  •     New routines SpinPermutationOperator and SpinPermutationSuperoperator implement general cyclic permutations and exchanges of spins. See the documentation parts 3 and 4.
  •     New routine MagneticQuantumNumber calculates the total magnetic quantum number (M-value) of a Ket, taken over all spins, or defined subsets. See the documentation part 3.
  •     Bug fixes.

Updates and Messages / SpinDynamica 2.8.1
« on: September 13, 2013, 06:02:09 PM »
SpinDynamica 2.8.1 has been released on

Updates and Messages / SpinDynamica 2.7.1
« on: July 24, 2013, 11:05:52 PM »
SpinDynamica 2.7.1 has been released here:

Updates and Messages / SpinDynamica 2.6.1
« on: April 28, 2013, 04:46:51 PM »
SpinDynamica 2.6.1 has now been released on

Updates and Messages / SpinDynamica 2.6.0
« on: March 18, 2013, 09:58:46 PM »
SpinDynamica 2.6.0 has been released here:

  • bug fixes and speed enhancements
  • parallel computing of EnsembleAverage

The parallelization of EnsembleAverage is implemented by default. It may be disabled by using the option Parallel->False. Numerical values such as Parallel->n implement the computation by distributing over n parallel kernels. The default Parallel->True distributes over all available parallel kernels.

Thanks to Andreas Brinkmann for help with the parallelization.

Examples / Spin 1 quadrupolar powder patterns
« on: December 20, 2012, 02:36:34 PM »
This notebook (which uses v2.5.5) shows how to calculate spin-1 powder patterns, including biaxiality (often referred to as "asymmetry").

Bug reports / Multiplying operators (a trap for the unwary)
« on: December 18, 2012, 02:12:36 PM »
Unexpected behaviour (including getting stuck) has been reported by users who attempt to multiply two operators using Times rather than Dot, i.e.

opI[1,"x"]*opI[2,"z"]  (incorrect)

rather than

opI[1,"x"].opI[2,"z"] (correct)

using Times ("*") for operators is illegal. Always use Dot (".") to multiply operators (and vectors, for that matter).

Times may however be used to multiply operators by numbers, for example

2 Pi * opI[1,"x"] (correct)  or
2 Pi opI[1,"x"].opI[2,"z"] (correct)

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