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Manuscript Title: Optimized Multiple Quantum MAS Lineshape Simulations in Solid State NMR
Authors: William J. Brouwer, Michael C. Davis, Karl T. Mueller
Program title: mqmasOPT
Catalogue identifier: AEEC_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 180(2009)1973
Programming language: C, OCTAVE.
Computer: UNIX/Linux.
Operating system: UNIX/Linux.
Has the code been vectorised or parallelized?: Yes
RAM: Example: (1597 powder angles)×(200 Samples)×(81 F2 frequency pts)×(31 F1 frequency points)= 3.5M, SMP AMD opteron
Keywords: Nuclear Magnetic Resonance, Multiple Quantum Magic Angle Spinning, OpenMP, Sobol sequence, quasi-random numbers, simulated annealing, distribution functions, quadrupole interaction.
PACS: 02.70.-c, 07.05.Tp, 32.30.Dx.
Classification: 2.3.

External routines: OCTAVE (http://www.gnu.org/software/octave/), GNU Scientific Library ( http://www.gnu.org/software/gsl/), OPENMP (http://openmp.org/wp/)

Nature of problem:
The optimal simulation and modeling of multiple quantum magic angle spinning NMR spectra, for general systems, especially those with mild to significant disorder. The approach outlined and implemented in C and OCTAVE also produces model parameter error estimates.

Solution method:
A model for each distinct chemical site is first proposed, for the individual contribution of crystallite orientations to the spectrum. This model is averaged over all powder angles[1], as well as the (stochastic) parameters; isotropic chemical shift and quadrupole coupling constant. The latter is accomplished via sampling from a bi-variate Gaussian distribution, using the Box-Muller algorithm to transform Sobol (quasi) random numbers[2]. A simulated annealing optimization is performed, and finally the non-linear jackknife[3] is applied in developing model parameter error estimates.

Additional comments:
The distribution contains a script, mqmasOpt.m, which runs in the OCTAVE language workspace.

Running time:
Example: (1597 powder angles)×(200 Samples)×(81 F2 frequency pts)×(31 F1 fre- quency points)=58.35 seconds, SMP AMD opteron

References:
[1] S. K. Zaremba, Annali di Matematica Pura ed Applicata 73, 293 (1966)
[2] H. Niederreiter, Random number generation and quasi-Monte Carlo methods, SIAM, 1992
[3] T. Fox, D. Hinkley, K. Larntz, Technometrics 22, 29 (1980)