[Wien] reg. RMT

[Santhy Jaiker]

Dear Wien2k users,
   
  I am facing a problem in optimization and mini due to RMT.   I want to optimize a crystal structure of AB2 compound.  I optimized the parameter RKmax, Kmesh, RMT, etc., and run the SCF calculation.  After seeing its force, which is higher than 5mRy/atom, i did the mini calculation. I got the stop error due to overlapping of sphere.  I changed the RMT of A and B from 2.2 to 2.  Now for the new RMT, I optimized Kmesh and RKmax value. Then, the calculation runs successfully and the force is also reduced around 1mRy/atom.  The next step, I did optimization job  (with mini –I –j “run_lapw –I –fc 1 –I 100” ) with varying volume from -2% to +2%.  It gives error due to overlapping of spheres even with -2% of volume changes.  For -1% volume also showed the same error. Then I tried with varying volume from -0.5 % to +0.5 % volume. The energy values decreases from +0.5% to –O.5%.  But I didn’t get the parabola.   
   
  Because of the above result, I am expecting the minimum energy configuration will be less than +0.5% volume change.  
   
  This is the current situation.  Further I have to reduce the RMT value or to change the reduced RMT (which I gave 3% reduction) value?
   
  Before going to scf calculation, is there any possibility or a thumb rule to find the approximate RMT value for corresponding crystal structure?  Because it is time consuming process, do find the appropriate RMT after mini.
   
  If the system have force greater than 5 mRy/atom, first I have do the mini then optimize the structure with varying volume or find the minimum energy configuration structure by varying volume and do the mini for that corresponding structure?
   



Regards,

Santhy Jaiker
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