different nn-table in VASP & WIEN

Message

tilak · #1 Post by **tilak** » Tue Feb 25, 2014 9:08 am

Dear Admin, could you please illustrate why the coordination of 18th atom with the 31st atom (table below) in VASP 5.2.3. does not gets the 6th coordination,
-----------------------------------VASP
17 0.250 0.250 0.097- 41 1.90 53 1.90 44 1.90 59 1.90 29 1.90 30 2.31 14 3.21 2 3.21 10 3.21 6 3.21
18 0.250 0.250 0.220- 30 1.89 42 1.90 54 1.90 45 1.90 60 1.90 3 3.20 7 3.20 11 3.20 15 3.20
19 0.250 0.250 0.345- 31 1.92 61 1.92 46 1.92 55 1.92 43 1.92 16 3.22 8 3.22 12 3.22 4 3.22
-------------------------------------------

whereas with the exactly same structure, we have got it (below)
--------------------------WIEN
ATOM: 18 EQUIV. 1 Co AT 0.25000 0.25000 0.22014
RMT( 18)=1.88000 AND RMT( 30)=1.67000 SUMS TO 3.55000 LT. NN-DIST= 3.56415
ATOM: 30 O AT 0.2500 0.2500 0.1649 IS 3.56415 A.U. 1.88607 ANG
ATOM: 42 O AT 0.2500 0.0000 0.2308 IS 3.59148 A.U. 1.90053 ANG
ATOM: 45 O AT 0.2500 0.5000 0.2308 IS 3.59148 A.U. 1.90053 ANG
ATOM: 54 O AT 0.0000 0.2500 0.2308 IS 3.59148 A.U. 1.90053 ANG
ATOM: 60 O AT 0.5000 0.2500 0.2308 IS 3.59149 A.U. 1.90053 ANG
ATOM: 31 O AT 0.2500 0.2500 0.2894 IS 4.47279 A.U. 2.36690 ANG
ATOM: 3 Bi AT 0.0000 0.0000 0.2729 IS 6.03902 A.U. 3.19571 ANG
ATOM: 7 Bi AT 0.0000 0.5000 0.2729 IS 6.03902 A.U. 3.19571 ANG
ATOM: 11 Bi AT 0.5000 0.0000 0.2729 IS 6.03905 A.U. 3.19573 ANG
ATOM: 15 Bi AT 0.5000 0.5000 0.2729 IS 6.03905 A.U. 3.19573 ANG
ATOM: 6 Bi AT 0.0000 0.5000 0.1506 IS 6.70967 A.U. 3.55060 ANG
ATOM: 10 Bi AT 0.5000 0.0000 0.1506 IS 6.70972 A.U. 3.55063 ANG
ATOM: 2 Bi AT 0.0000 0.0000 0.1506 IS 6.70980 A.U. 3.55067 ANG
ATOM: 14 Bi AT 0.5000 0.5000 0.1506 IS 6.70985 A.U. 3.55070 ANG
ATOM: 24 Co AT -0.2500 0.2500 0.2201 IS 7.05057 A.U. 3.73100 ANG
ATOM: 21 Co AT 0.2500 -0.2500 0.2201 IS 7.05057 A.U. 3.73100 ANG
ATOM: 21 Co AT 0.2500 0.7500 0.2201 IS 7.05057 A.U. 3.73100 ANG
ATOM: 24 Co AT 0.7500 0.2500 0.2201 IS 7.05057 A.U. 3.73100 ANG
Atom 18 equiv 1 Co Bond-Valence Sum 2.81 2.96
-----------------------------------------------------------------

As a result, I have very much different magnetic behaviour for the 18th atom.............!! According to my analysis WIEN gives the correct result.

Thanks for comments,
Tilak

#2 Post by **admin** » Tue Feb 25, 2014 11:59 am

A limited number of neighbours is printed in the table. The limiting distance used for the calculation of neighbours is in VASP different from that used in WIEN. Therefore VASP prints 5 neighbours and WIEN prints 6 neighbours.

tilak · #3 Post by **tilak** » Tue Feb 25, 2014 5:28 pm

Thank you very much.

Is there any way to increase some parameter in VASP to manage "limiting distance" part, so that I could have exactly similar neighbours.

Regards
Tilak

#4 Post by **admin** » Thu Feb 27, 2014 11:41 am

The limiting distance is defined using wigner-seitz radii (poscar.F, line 956; DIS=RWIGS1+RWIGS2).
[ Edited Thu Feb 27 2014, 11:44AM ]