[Pw_forum] tetrahedra and vc-relax

Giuseppe Mattioli giuseppe.mattioli at ism.cnr.it
Wed Oct 18 10:48:15 CEST 2017

Dear Chiara
You should not use occupations='tetrahedra' for relax or vc-relax  
calculations! The reason is clearly stated in the pw.x manual. Use  
smearing instead

    Variable:       occupations

    Type:           CHARACTER
                    Available options are:

                    'smearing' :
                         gaussian smearing for metals;
                         see variables "smearing" and "degauss"

                    'tetrahedra' :
                         especially suited for calculation of DOS
                         (see P.E. Bloechl, PRB 49, 16223 (1994)).
                         Requires uniform grid of k-points,
                         automatically generated (see below).
                         Not suitable (because not variational) for
                         force/optimization/dynamics calculations.

                    'fixed' :
                         for insulators with a gap

                    'from_input' :
                         The occupation are read from input file,
                         card "OCCUPATIONS". Option valid only for a
                         single k-point, requires "nbnd" to be set
                         in input. Occupations should be consistent
                         with the value of "tot_charge".


Quoting chiara.ricca at dcb.unibe.ch:

> Dear all,
> I'm trying to perform a "vc-relax" calculation using the tetrahedron  
> method with QE v 6.1.
> The calculation stops after having printed the final geometry,  
> during the final scf step.
> It does not write any error and the scheduler only reports a  
> segmentation fault.
> I have tried with both tetrahedra and tetrahedra_opt, but I have the  
> same issue.
> The problem is not there if I do a "relax" calculation.
> Please find attached, the input and output of an example.
> Thanks in advance!
> Regards,
> Chiara Ricca
> ---
> Postdoctoral fellow
> University of Bern

Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>

More information about the users mailing list