[Pw_forum] error in total energy calculation

[Jibiao Li]

Dear Dhaval Satikunvar,


This kind of zigzag in energy may not be related to any errors in calculations. Why not use a fitting procedure to obtain the smooth energy minimum?


Jibiao Li




------------------ Original ------------------
From:  "Dhaval Satikunvar";<dhavalsatikunvar at gmail.com>;
Date:  Thu, Aug 24, 2017 03:08 PM
To:  "pw_forum"<pw_forum at pwscf.org>; 

Subject:  [Pw_forum] error in total energy calculation



Dear all,


I am new to quantum espresso. I have done a few calculations on total energy of cubic structures and I am getting results. While calculating energy of rhombohedral structure, I am getting zig zag in total energy - lattice parameter data instead of a sharp minimum. I am keeping a=b=c and alpha=beta=gamma= 89'30" sat this stage. Please help me to rectify this error. Output file is pasted below. First column is lattice parameter and second is corresponding energy.  

6.1 -120.559917
6.2 -120.603774
6.3 -120.623712
6.4 -120.659428
6.5 -120.679109
6.6 -120.676959
6.7 -120.689501
6.8 -120.729527
6.9 -120.749782
7.0 -120.784868
7.1 -120.770751
7.2 -120.746599
7.3 -120.820501
7.4 -120.776595
7.5 -120.775767


Thanks in anticipation  

-- 
Dhaval Satikunvar
Department of Physics,

Sardar Patel University, VVN
PIN: 388120
Phone: 09426279465
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