[Pw_forum] problem with k-points
eminekb at yahoo.com
Sun Dec 10 18:27:56 CET 2006
I would like to say you may find example 5 useful for your questions about k points.
There you can find how to enter k points manually for scf and nscf calculations.
I think it is necessary to check the weight of k points for scf,
but for nscf band structure calc. as in example 05 that may not have any significance,
For the elastic constants,
using the well known strain-stress relation
and elastic energy density expression, is the first way that comes to my mind.
The convention about which strain to use to obtain which elastic constant,
is probably told in many references that one can check in the literature.
For a simple explanation for a simple system,
you can take a look at
Phys. Rev. B 60, 791 - 799 (1999) and erratum.
I am a new user of QE, and not even a grad student yet,
so if I said sth wrong, I hope more experienced users will correct me.
Sanjeev Kumar Gupta <sanjeev0302 at rediffmail.com> wrote:
Thanking you Amin,
>>This is done in espresso code automatically for scf and nscf but for plotting band structure you should do it manually>>
But what will be the maximum and minimum range of the k-point for band calculation and also you said in earlier suggestion that, for scf and nscf it is automatic,but we want to do manually the how we will proceeds?
>>I thought it is possible.negative or positive Fermi energy doesn't have physical meaning>>
sorry, for again same question, what is significance of negative fermi energy is any relation in other calculation.
I want to find out the elastic constant for my system, how we will proceeds?
On Sun, 10 Dec 2006 Amin Babazadeh wrote :
>On 9 Dec 2006 04:44:31 -0000, Sanjeev Kumar Gupta <
>sanjeev0302 at rediffmail.com> wrote:
>>i am sanjeev gupta, from india, working DFT calculation via
>>Quantum-Espresso-3.1.1. I have doubts with k-ponits,
>>1)How we choose k-points for diiferent system?
>dis is done in espresso code automatically for scf and nscf but for plotting
>band structure you should do it manually
>2)Is possible fermi energy negative for noble nitrides?
>3)Is neccessary same k-points for scf and nscf cycle or phX,phL and phG.?
>>no you can change it.for scf and nscf.usually the kpoint for scf
>>calculation is smaller than nscf.about phX,phL and phG i don't have any
>>Sanjeev Kumar Gupta
>>Junior Research Fellow (DAE-BRNS)
>>Computational Condensed Matter Physics Lab.(CCMP)
>>Department of Physics, Faculty of Science,
>>The M.S.University of Baroda, Vadodara - 390 002.
>>Ph.No: +91-265-279 5339 (O) extn: 30-25
>>Email: sanjeev0302 at rediffmail.com
>> sanjeev0302 at yahoo.co.in
>> skgupta-phy at msubaroda.ac.in
>>Dr. Vikram Sarabhai Hall,
>>Room No.-95, Boys' Hostel,M.S.University Campus,
Sanjeev Kumar Gupta
Junior Research Fellow (DAE-BRNS)
Computational Condensed Matter Physics Lab.(CCMP)
Department of Physics, Faculty of Science,
The M.S.University of Baroda, Vadodara - 390 002.
Ph.No: +91-265-279 5339 (O) extn: 30-25
Email: sanjeev0302 at rediffmail.com
sanjeev0302 at yahoo.co.in
skgupta-phy at msubaroda.ac.in
Dr. Vikram Sarabhai Hall,
Room No.-95, Boys' Hostel,M.S.University Campus,
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