Calculation of INS spectra using a-CLIMAX

Rigorous modelling of INS from first principles

  • It uses the isolated molecule approach for the study of molecular solids.
  • For extended solid calculations the approximation is not longer necessary since there is no distinction between external and internal modes.

Calculation of INS spectra, the Scattering Law

 

scattering law

Scattering Law
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Calculation of INS spectra using CASTEP

The normal modes are calculated for a large grid of points in the reciprocal space. In this example, the lattice was sampled as a 32x32x48 grid (the symmetry of the system makes that number smaller).
The INS spectra is generated from the eigenvectors and eigenvalues on every point in the grid.

 

a-CLIMAX example

a-CLIMAX example
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This is an example of an INS spectrum of MgH2 calculated using CASTEP (full phonon calculation using the interpolation algorithm) and a-CLIMAX.

Citation

Ramirez-Cuesta, A. J. aCLIMAX 4.0.1, The new version of the software for analyzing and interpreting INS spectra. Computer Physics Communications 2004, 157 (3), 226-238.

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