different nn distances !

[tilak]

Dear VASP Users,

Recently, I have seen some problem of using the VASP 5.2.12 package. I do not know if it is any BUG related problem !!

I was interested to do a calculation on the CaXYZ (some complex oxide, having 20 elements) containing "Ca" as the 1st element. When I do initialize the calculation, I have nn-distances for "Ca" is as below:
-------------------
1 0.000 0.000 0.000- 5 3.27 6 3.27 7 3.27 8 3.27 6 3.27 7 3.27 8 3.27 5 3.27
---------------------------

Now, I am interested to another sample LaXYZ (same space group than CaXYZ, complex oxide, having 20 elements as well), where the "Ca" is replaced by "La" at the same position. After initialization, I have nn-distances as below:
--------------------
1 0.000 0.000 0.000- 14 2.63 15 2.63 10 2.63 11 2.63 18 2.63 19 2.63 9 2.63 12 2.63
17 2.63 13 2.63 16 2.63 20 2.63 5 3.27 6 3.27 7 3.27 8 3.27
------------------------------------------
Why two different type of nn-distances !!!! ? I have exactly same inputs in both, except that I did necessary change in POTCAR, only.

According to the Expt. data, the second case is correct about the coordination of La and Ca and also checked with VESTA. How can I get correct nn-distances for the first case ?

Thank you very much
Tilak

[tilak]

Dear Users and Admin,

I have figured out the problem that was posted an hour before. Solution is: Just I have to change the type of Ca pseudopotential from Ca_sv to Ca_pv !!

Now, I have good nn-distances !! Only, the difference I have seen that the Ca_pv is more softer than the Ca_sv !!

Could I have a brief explanation, please ? If someone interested in particularly with Ca_sv PP, what will happen ?

Best Regards,
Tilak