displacement¶
- sisl.physics.phonon.displacement(mode, hw, mass)[source]¶
Calculate real-space displacements for a given mode (in units of the characteristic length)
The displacements per mode may be written as:
\[\mathbf{u}_{i\alpha} = \epsilon_{i\alpha}\sqrt{\frac{\hbar}{m_i \omega}}\]where \(i\) is the atomic index.
Even for negative frequencies the characteristic length is calculated for use of non-equilibrium modes.
- Parameters
mode (array_like) – vectors describing the phonon modes, 2nd dimension contains the modes. In case of degenerate modes the vectors may be rotated upon return.
hw (array_like) – frequencies of the modes, for any negative frequency the returned displacement will be 0.
mass (array_like) – masses for the atoms (has to have length
mode.shape[1] // 3
- Returns
displacements per mode with final dimension
(mode.shape[0], 3), displacements are in Ang- Return type