v0.6.5

• New Features:

  • Kinematic constraints have been implemented for 2-D S(q,w)-like data.

    • A function euphonic.spectra.apply_kinematic_constraints(Spectrum2d, **kwargs) -> Spectrum2D
      is implemented which masks out inaccessible data, replacing it with NaN.
    • Both direct-geometry and indirect-geometry are supported, by
      using the appropriate argument to set incident or final neutron energy.
    • This function is exposed to the euphonic-powder-map tool, so these
      plots can be produced directly from the CLI.
    • Some parameters from real-world instruments are collected in the
      documentation for convenience.

  • There is a new function euphonic.util.convert_fc_phases, which converts
    a force constants matrix which uses the atom coordinates in the phase
    during interpolation (Phonopy-like), to one which uses the cell origin
    coordinates (Euphonic, CASTEP-like).

  • When importing q-point modes or frequencies from a CASTEP .phonon
    file, a new option (average_repeat_points=True) allows
    repeated entries (with the same q-point index) to be identified
    and their weights divided down by the number of entries. This
    option should give better statistics for sampling meshes that
    include the Gamma-point with LO-TO splitting.

• Improvements:

  • Documentation on the shape and format of the force constants, and how to
    read them from other programs has been improved.

  • The euphonic.util.get_qpoint_labels function, which is called when
    importing band-structure data to identify and label significant points,
    primarily identifies these points by searching for turning-points
    in the band path. The function will now also pick up any q-point
    that appears twice in succession. This is a common convention in
    band-structure calculations and helps with edge-cases such as when
    the path passes through a high-symmetry point without changing
    direction. This may pick up some previously-missing points in
    band-structure plots generated with euphonic-dispersion and
    euphonic-intensity-map

• Bug fixes:

  • Allow read of phonopy.yaml quantities in 'au' (bohr) units.
    Previously this was interpreted as an astronomical unit by Pint.