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### Messages - Christian Bengs

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« on: February 21, 2020, 04:31:01 PM »

-The function may be used to calculate adiabatic SLIC or APSOC profiles, for example.

See the original publication by our friends from Novosibirsk (Rodin et al., https://doi.org/10.1063/1.5079436) for technical details.

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« on: January 15, 2020, 12:37:10 PM »

-The add on calculates dual-pairings between irreducible representations of S(n) and SO(3) < U(n)
-Irreducible representations of S(n) are identified with Young-Tableaux
-SO(3) irreducible representations are characterised by a total angular momentum quantum number.

Such identifications are useful for the determination of symmetry selection rules for long-lived spin operators.

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##### Simulations / Re: Commutator[], Matrixexponential, Subspace
« on: February 06, 2019, 10:18:05 AM »
Hey Hannes,

1) There is really no need to let SpinDynamica know what a commutator equals when constructing the matrix representation of a superoperator. The commutation relations will be dealt with "automatically".

2) There is really no way to reduce the size of the matrix unless your Hamiltonian might display some symmetry. In this case you can define your own basis and focus on the relevant subspace. A useful syntax to order the matrix into its subspaces is as follows:

Flatten[ConnectedComponents[Rule @@@MatrixRepresentation[H]]["NonzeroPositions"]]]

This will return a permutation that permutes the Hamiltonian into block-diagonal form.

3) The reason the last calculation doesn't stop is because the analytic calculation of the matrix exponential takes very long. You may circumvent the problem by first calculating the matrix exponential in a "simple" basis and then transform back into your preferred basis.

4) Unfortunately SpinDynamica has no capabilities to restrict calculations to a certain subspace atm.

kind regards,

Christian

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##### Updates and Messages / SpinDynamica 3.3.2 released
« on: February 06, 2019, 10:10:47 AM »
SpinDynamica 3.3.2 has been released.

–EigenBasis now takes TargetBasis as an optional argument. The calculated EigenBasis and TargetBasis will be aligned as closely as possible. This should be useful for analysis of adiabatic calculations.
–Some bug fixes and speed improvements to the basis construction of spins with I>1/2.
–The functions SingleTransitionOperator, CoherenceOperator and PopulationOperator now allow for specification of a basis. See the documentation for more details.

Check out the SpinDynamica website for the new release: http://www.spindynamica.soton.ac.uk/2019/02/06/spindynamica-3-3-2/

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##### Updates and Messages / SpinDynamica 3.3.1 released
« on: November 06, 2018, 11:53:24 AM »
SpinDynamica 3.3.1 has been released.

-The recent update of SpinDynamica introduced some problems with WignerD, these bugs have been fixed now.
-The functionality of CorrelatedEigensystems has been extended to support Liouvillians and arbitrary sets of matrices.

Check out the SpinDynamica website for the new release: http://www.spindynamica.soton.ac.uk/2018/11/06/spindynamica-3-3-1/

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##### Updates and Messages / SpinDynamica 3.2.1 released
« on: October 08, 2018, 11:52:08 AM »
SpinDynamica 3.2.1 has been released.

-SpinDynamica now allows for variable degrees of error trapping via UserLevel. Less error trapping leads to speed improvements for some routines.
-The routine MaximizeTransformationAmplitude has been added to SpinDynamica. MaximizeTransformationAmplitude numerically optimizes a TransformationAmplitude with respect to a set of parameters.
-Several bugs have been fixed, most notably bugs related to the COMPUTE algorithm. Thanks letting us know about these issues.

Check out the SpinDynamica website for a couple more details: http://www.spindynamica.soton.ac.uk/2018/10/08/spindynamica-3-2-1/

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##### Updates and Messages / SpinDynamica 3.1.0 released
« on: February 26, 2018, 03:23:55 PM »
SpinDynamica 3.1.0 has been released.

There are a couple of new features.

-SpinDynamica now contains several new routines for the analysis of adiabatic events (see part 11 of the documentation).
-Documentation on highly polarized spin-systems has been addded (see part 10 of the documentation).
-TransformationAmplitudeTable now supports two or more parameter specifications.
-Introduction of LeftMultiplicationSuperoperator and RightMultiplicationSuperoperator.

A more detailed description of the changes may be found here: http://www.spindynamica.soton.ac.uk/2018/02/26/spindynamica-3-1-0-with-a-couple-new-features/