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

Type: real
Default: 1.00000000E-002 [bohr]

Description: Specify the increment to be used to construct the HESSIAN with finite difference method

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FULLY_PERIODIC

Type: logical
Default: F
Lone keyword: T

Description: Avoids to clean rotations from the Hessian matrix.

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INTENSITIES

Type: logical
Default: F
Lone keyword: T

Description: 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

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NPROC_REP

Type: integer
Default: 1

Description: 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

Mentions: ⭐Simulating Vibronic Effects in Optical Spectra

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PROC_DIST_TYPE

Type: enum
Default: BLOCKED
Usage: PROC_DIST_TYPE (INTERLEAVED|BLOCKED)

Description: Specify the topology of the mapping of processors into replicas.

Valid values:

• INTERLEAVED Interleaved distribution

• BLOCKED Blocked distribution

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TC_PRESSURE

Type: real
Default: 1.01325000E+005 [Pa]

Description: Pressure for the calculation of the thermochemical data

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TC_TEMPERATURE

Type: real
Default: 2.73150000E+002 [K]
Usage: tc_temperature 325.0

Description: Temperature for the calculation of the thermochemical data

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THERMOCHEMISTRY

Type: logical
Default: F
Lone keyword: T

Description: Calculation of the thermochemical data. Valid for molecules in the gas phase, not supporting phonon frequencies at general q-points beyond wave vector q at gamma point. Based on the rigid-rotor harmonic oscillator (RRHO) model, which is known to break down if very low vibrational frequencies are present in a flexible system.

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