# INITIAL_VIBRATION

References: West2006

Controls the set of parameters for MD initialisation based on vibration analysis data. The starting atomic coordinates should be based on the relaxed positions obtained from a previous geometry/cell optimisation calculation, and the vibrational frequencies and displacements data should be obtained from a vibrational analysis calculation done based on the relaxed coordinates. The MD initialisation process expects the user has performed both geometry optimisation and vibrational analysis before hand, and won’t perform those calculations automatically [Edit on GitHub]

## Keywords

- PHASE

- VIB_EIGS_FILE_NAME

## Keyword descriptions

PHASE: real = -1.00000000E+000

  Usage: PHASE <REAL>

  Controls the initial ratio of potential and kinetic contribution to the total energy. The contribution is determined by COS2(2piPHASE) for potential energy, and SIN2(2piPHASE) for kinetic energy. If PHASE is negative, then for each vibration mode the phase is determined randomly. Otherwise, PHASE must be between 0.0 and 1.0 and will be the same for all vibration modes. If value > 1.0 it will just be treated as 1.0. For example, setting PHASE = 0.25 would set all modes to begin with entirely kinetic energy — in other words, the initial atomic positions will remain at their optimised location [Edit on GitHub]

VIB_EIGS_FILE_NAME: string

  Usage: VIB_EIGS_FILE_NAME <FILENAME>

  The file name of vibrational frequency (eigenvalue) and displacement (eigenvector) data calculated from the a vibrational analysis calculation done previously. This file must be the same unformatted binary file as referred to by VIBRATIONAL_ANALYSIS%PRINT%CARTESIAN_EIGS keyword. If this keyword is not explicitly defined by the user, then the default file name of: <project_name>-<CARTESIAN_EIGS_FILENAME>.eig will be used [Edit on GitHub]