Linear Response Functions

Contents

Linear Response Functions#

Available Methods#

Linear response functions are available for:

Example Input File#

An example using CCS is given below:

@method settings
basis: STO-3G
@end

@memory
max_mem: 1
@end

@jobs
task: ccs
@end

@ccs
restart: False
solver_thresh: 1.0E-12
operators: DIPLEN ANGMOM
frequency: 0.1
ratio: 1 -1
asym: False
@end

@scf
conv_thresh: 1.0E-12
@end

@molecule
charge: 0
multiplicity: 1
units: bohr
xyz:
O        0.0000000000    0.0000000000    0.0000000000
H        0.0000000000    1.4304281903    1.1071565216
H        0.0000000000   -1.4304281903    1.1071565216
@end

Relevant Keywords#

`operators`
Description	Operators used for response functions. - Linear response: Provide two operators - Quadratic response: Provide three operators - Cubic response: Provide four operators
Type	str
Default	DIPLEN DIPLEN
Options	- DIPLEN: Dipole integrals in the length gauge - ANGMOM: Angular momentum integrals - DIPVEL: Dipole integrals in the velocity gauge

`frequency`
Description	Defines which frequencies to calculate response functions for in atomic units.
Type	float(s)
Default	0
Options	- If 1 or 2 value(s) are given: Calculate for the listed frequency (frequencies) - If 3 values are given: start stop step

`ratio`
Description	Ratios of frequencies for response functions. - Example for second harmonic generation: 2 -1 -1 - Example for third harmonic generation: 3 -1 -1 -1
Type	floats
Default	None
Requirements	Must have equivalent length to the `operators` keyword The sum of all ratios must be equal to zero

`asym`
Description	Use the asymmetric formulation in which response multipliers are used for linear response functions.
Type	bool
Default	False
Availability	Linear response: `CCS` `CC2` `CCSD`

`dipole_pol`
Description	Calculates the components of the polarizability as well as the isotropic and anisotropic polarizability at the given frequency.
Type	bool
Default	False