Variables

From The Yambo Project
Revision as of 16:23, 27 March 2017 by Conor (talk | contribs) (→‎Units)
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Units

  • Integer = any positive integer value
  • Energy = RL (number of G-vectors), Ha, mHa (Hartree atomic units), Ry (Rydberg atomic units), eV (electron volts)
  • E range
  • Blah = dsfa

Formats

  • Range = Lower limit | Upper limit, in the specified Unit
  • Int range = Lower limit | Upper limit, integer values
  • Vector =

% x | y | z |, in cartesian coordinates %

Initialization

Variable: MaxGvecs (Units: Energy) Meaning: Number of G-vectors in screening
Tip: This determines the size of the dielectric matrix in G-space. Needed for inclusion of local field effects. It should be much smaller than the number of G-vectors needed to expand the wavefunctions. It needs careful convergence.

Optics

Variable: FFTGvecs (Units: RL) Meaning: Number of G-vectors used in expanding the wavefunctions and in FFT transforms
Tip: It needs careful convergence. Determines the memory needed.

Variable: NGBlkXd (Units: RL) Meaning: Number of G-vectors in the screening.
Tip: Determines the size of the dielectric matrix in G-space. Needed for inclusion of local field effects. It should be much smaller than the number of G-vectors needed to expand the wavefunctions. It needs careful convergence.

Variable: ETStpsX (Units: integer) Meaning: Number of energy steps.
Tip: Determines the number of steps in energy the response function/spectrum is computed for in the desired range defined by EnRngeX. Has little effect on memory or time.

EnRngeXd/Xs (Units: Energy, Format: Lower limit, Upper limit)
Meaning: Energy range the spectrum is calculated across.
Tip: Energy range

GW

Variable: EXXRLvcs (Units: RL) Meaning: Number of G-vectors used in the sum of the exchange self-energy Sx.
Tip: It needs careful convergence: not particularly time consuming, large values can be used to ensure convergence.

Variable: QPkrange (Units: Integers) Meaning: First and last Indexes of kpoints and bands the slef energy correction is calculated
Tip: If interested in non consecutive kpoints or bands multiple rows can be also considered