[QE-users] Wavefunctions not readable from SCF in band structure calculation

[Paolo Giannozzi]

On 9/27/2025 8:26 PM, Sergio Correal Lopez via users wrote:

> I then tried to do a band structure calculation, which is supposed to 
> read the charge density from the SCF Out dir.

it does

>  However, I get:
> *Wavefunctions not found or not readable, recomputing them from scratch*

this means that you have instructed the code to read the wavefunctions 
of the scf calculation. You shouldn't: this isn't the way non-scf 
calculations work. Just take the scf input, replace calculation='scf' 
with 'bands', set the desired number of bands and the desired list of 
k-points. Don't specify 'startingwfc' or 'startingpot'. Don't use 
'wfccir' unless you have a good reason.
> so the calculation turns out to be too computationally expensivethis is unavoidable: a band-structure calculation is often as expensive 
as a scf one, or even more, depending upon the number of required bands 
and the k-point grid

Paolo


.
> I have ensured the Out directory is the same for SCF and bands calculations. I 
> have also tried setting
> 
> 
> startingwfc = 'file'
> 
> startingpot = 'file'
> 
> and wfcdir = 'Out' or wfcdir = 'Out/system.save' but nothing seems to 
> work. Here are the relevant inputs/outputs:
> 
> 
> https://drive.google.com/drive/ 
> folders/1keS1DFLjvrwuvZ61wjaPV6JPQ47aTPFE?usp=sharing <https:// 
> drive.google.com/drive/folders/1keS1DFLjvrwuvZ61wjaPV6JPQ47aTPFE? 
> usp=sharing>
> 
> 
> I kindly ask for advice.
> 
> Best,
> 
> Sergio Correal
> 
> PhD Student, UC San Diego
> 
> 
> 
> 
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216