Polarizabilities

Name BornChargeSumRuleCorrection
Section Linear Response::Polarizabilities
Type logical
Default true

Enforce the acoustic sum rule by distributing the excess sum of Born charges equally among the atoms. Sum rule: $\sum_{\alpha} Z^{*}_{\alpha, i, j} = Z_{\rm tot} \delta_{ij}$. Violation of the sum rule may be caused by inadequate spacing, box size (in finite directions), or k-point sampling (in periodic directions).

Name EMCalcBornCharges
Section Linear Response::Polarizabilities
Type logical
Default false

Calculate linear-response Born effective charges from electric perturbation (experimental).

Name EMCalcMagnetooptics
Section Linear Response::Polarizabilities
Type logical
Default false

Calculate magneto-optical response.

Name EMCalcRotatoryResponse
Section Linear Response::Polarizabilities
Type logical
Default false

Calculate circular-dichroism spectrum from electric perturbation, and write to file rotatory_strength.

Name EMEta
Section Linear Response::Polarizabilities
Type float
Default 0.0

The imaginary part of the frequency, effectively a Lorentzian broadening for peaks in the spectrum. It can help convergence of the SCF cycle for the Sternheimer equation when on a resonance, and it can be used as a positive infinitesimal to get the imaginary parts of response functions at poles. In units of energy. Cannot be negative.

Name EMForceNoKdotP
Section Linear Response::Polarizabilities
Type logical
Default false

If the system is periodic, by default wavefunctions from a previous kdotp run will be read, to be used in the formulas for the polarizability and hyperpolarizability in the quantum theory of polarization. For testing purposes, you can set this variable to true to disregard the kdotp run, and use the formulas for the finite system. This variable has no effect for a finite system.

Name EMFreqs
Section Linear Response::Polarizabilities
Type block

This block defines for which frequencies the polarizabilities will be calculated. If it is not present, the static ($\omega = 0$) response is calculated.

Each row of the block indicates a sequence of frequency values, the first column is an integer that indicates the number of steps, the second number is the initial frequency, and the third number the final frequency. If the first number is one, then only the initial value is considered. The block can have any number of rows. Consider the next example:

%EMFreqs
31 | 0.0 | 1.0
1 | 0.32
%

Name EMFreqsSort
Section Linear Response::Polarizabilities
Type logical
Default true

If true, the frequencies specified by the EMFreqs block are sorted, so that they are calculated in increasing order. Can be set to false to use the order as stated, in case this makes better use of available restart information.

Name EMHyperpol
Section Linear Response::Polarizabilities
Type block

This block describes the multiples of the frequency used for the dynamic hyperpolarizability. The results are written to the file beta in the directory for the first multiple. There must be three factors, summing to zero: $\omega_1 + \omega_2 + \omega_3 = 0$. For example, for second-harmonic generation, you could use 1 | 1 | -2.

Name EMKPointOutput
Section Linear Response::Polarizabilities
Type logical
Default false

Give in the output contributions of different k-points to the dielectric constant. Can be also used for magneto-optical effects.

Name EMMagnetoopticsNoHVar
Section Linear Response::Polarizabilities
Type logical
Default true

Exclude corrections to the exchange-correlation and Hartree terms from consideration of perturbations induced by a magnetic field

Name EMOccupiedResponse
Section Linear Response::Polarizabilities
Type logical
Default false

Solve for full response without projector into unoccupied subspace. Not possible if there are partial occupations. When EMHyperpol is set for a periodic system, this variable is ignored and the full response is always calculated.

Name EMPerturbationType
Section Linear Response::Polarizabilities
Type integer
Default electric

Which perturbation to consider for electromagnetic linear response.

Options:

• electric:
  Electric perturbation used to calculate electric polarizabilities and hyperpolarizabilities.
  
• magnetic:
  Magnetic perturbation used to calculate magnetic susceptibilities.
  
• none:
  Zero perturbation, for use in testing.
  

Name EMWavefunctionsFromScratch
Section Linear Response::Polarizabilities
Type logical
Default false

Do not use saved linear-response wavefunctions from a previous run as starting guess. Instead initialize to zero as in FromScratch, but restart densities will still be used. Restart wavefunctions from a very different frequency can hinder convergence.

Name vdWNPoints
Section Linear Response::Polarizabilities
Type integer
Default 6

How many points to use in the Gauss-Legendre integration to obtain the van der Waals coefficients.