Calculation of INS spectra using a-CLIMAX
29 Oct 2009



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


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.


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.