# VIBRATIONAL_ANALYSIS

Section to setup parameters to perform a Normal Modes, vibrational, or phonon analysis. Vibrations are computed using finite differences, which implies a very tight (e.g. 1E-8) threshold is needed for EPS_SCF to get accurate low frequencies. The analysis assumes a stationary state (minimum or TS), i.e. tight geometry optimization (MAX_FORCE) is needed as well. [Edit on GitHub]

Subsections

- MODE_SELECTIVE
- PRINT

## Keywords

- DX

- FULLY_PERIODIC

- INTENSITIES

- NPROC_REP

- PROC_DIST_TYPE

- TC_PRESSURE

- TC_TEMPERATURE

- THERMOCHEMISTRY

## Keyword descriptions

DX: real = 1.00000000E-002 [bohr]

  Specify the increment to be used to construct the HESSIAN with finite difference method [Edit on GitHub]

FULLY_PERIODIC: logical = F

  Lone keyword: `T`

  Avoids to clean rotations from the Hessian matrix. [Edit on GitHub]

INTENSITIES: logical = F

  Lone keyword: `T`

  Calculation of the IR/Raman-Intensities. Calculation of dipoles and/or polarizabilities have to be specified explicitly in DFT/PRINT/MOMENTS and/or PROPERTIES/LINRES/POLAR [Edit on GitHub]

NPROC_REP: integer = 1

  Specify the number of processors to be used per replica environment (for parallel runs). In case of mode selective calculations more than one replica will start a block Davidson algorithm to track more than only one frequency [Edit on GitHub]

PROC_DIST_TYPE: enum = BLOCKED

  Usage: PROC_DIST_TYPE (INTERLEAVED|BLOCKED)

  Valid values:

  - `INTERLEAVED` Interleaved distribution

  - `BLOCKED` Blocked distribution

  Specify the topology of the mapping of processors into replicas. [Edit on GitHub]

TC_PRESSURE: real = 1.01325000E+005 [Pa]

  Pressure for the calculation of the thermochemical data [Edit on GitHub]

TC_TEMPERATURE: real = 2.73150000E+002 [K]

  Usage: tc_temperature 325.0

  Temperature for the calculation of the thermochemical data [Edit on GitHub]

THERMOCHEMISTRY: logical = F

  Lone keyword: `T`

  Calculation of the thermochemical data. Valid for molecules in the gas phase. [Edit on GitHub]