Accuracy and Efficiency¶
Given a Model Hamiltonian, the most important aspects determining the accuracy of a Band calculation are:
Also important, but to a lesser degree, are the following aspects:
- Numerical Integration (BeckeGrid)
- Density fitting (ZlmFit)
- Basis-set confinement (SoftConfinement)
- SCF convergence (Convergence)
- Hartree–Fock Resolution of the Identity (RIHartreeFock) (only for hybrid functionals)
The CPU time and memory requirements strongly depends on these options, as does the accuracy of the results.
General NumericalQuality
A simple way of tweaking the accuracy of the calculation is via the NumericalQuality key. This sets the quality of several technical aspects of a Band calculation (with the notable exception of the basis set)
NumericalQuality [Basic | Normal | Good | VeryGood | Excellent]
NumericalQualityType: Multiple Choice Default value: Normal Options: [Basic, Normal, Good, VeryGood, Excellent] Description: Set the quality of several important technical aspects of a BAND calculation (with the notable exception of the basis set). It sets the quality of: BeckeGrid (numerical integration), ZlmFit (density fitting), KSpace (reciprocal space integration), and SoftConfinement (basis set confinement). Note: the quality defined in the block of a specific technical aspects supersedes the value defined in NumericalQuality (e.g. if I specify ‘NumericalQuality Basic’ and ‘BeckeGrid%Quality Good’, the quality of the BeckeGrid will be ‘Good’)