[QE-users] increasing precision of band energies

[Paolo Giannozzi]

On 06/05/2023 14:43, agaur wrote:

> By default band energies calculated in QE are listed up to 5th decimal 
> place. Is it possible to increase the precision to 8th decimal place? 

just increase the format in PW/src/print_ks_energies.f90 and recompile. 
Alternatively, the output xml data file (data-file-schema.xml) contains 
the eigenvalues with all significant figures.

> I am trying to find some energy differences in the range of micro-eV and 
> higher precision would definitely be useful.
You may want to carefully verify how "significant" the figures beyond 
the first 4 or 5 are. In order to get reproducible numbers you need a 
very tight scf convergence. Unlike total energy, Kohn-Sham eigenvalue 
are not variational quantities. Printing more significant figures is 
just the first step.

Paolo
-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216