[Wien] ion relaxation for PrBa2Cu3O7 system

[Jorissen Kevin]

In a SCF iteration, the code does not calculate the full force, but omits one component to save time.  It converges the partial force that is calculated (to 1 mRy/au in your case - specified as -fc 1).  When this is done, the code runs once more to determine the correct total force (i.e., add the contribution that was omitted earlier).  That produces the last number (14 in your case), which is the correct converged force (that will a.o. be used to optimize the structure).
 
hope this helps,
 
Kevin.
 
 
 
 
Kevin Jorissen
 
 
new contact address !!
 
Kevin Jorissen
University of Washington
Dept. of Physics
Box 351560
Seattle, WA-98195-1560
U.S.A.
 
phone  +1 206 543 3904
fax      +1 206 685 0635
 
e-mail kevin.jorissen at ua.ac.be
web page http://fraangelico.phys.washington.edu/~jorissen
 

________________________________

Van: wien-bounces at zeus.theochem.tuwien.ac.at namens vahid ghanbarian
Verzonden: di 4-10-2005 3:33
Aan: wien at zeus.theochem.tuwien.ac.at
Onderwerp: [Wien] ion relaxation for PrBa2Cu3O7 system



Dear wien_2k users

I want to do ion relaxation for PrBa2Cu3O7 system. I used NEWT methods and this command: min -j'run_lapw -I -i 99 -fc 1'.

In case_n.scf (n=1,2,3,...) the forces have very large fluctuation in final iteration. For example the forces of 4.ATOM in case_3.scf are :

Iteration: 12      13       14

FOR004: 33.467      33.079      3.214

(14 is the final iteration)

I have one important question .When -fc 1 was used, why after a large fluctuation of forces in final iteration of scf n (n=1,2,3,...) (about 30 mRy/au >>1)the program converged (and went to n+1 step)?

Thanks

Vahid Ghanbarian.

University of Tehran. IRAN. 

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