Bader analysis on surface

[cwandtj]

Hello.
I did Bader charge analysis on my oxide surface.
I used double numbers of NGXF, NGYF, and NGZF.

The problem is atomic volumes for surface atoms are too large and corresponding charge values are also different and I don't know whether the results are OK or not.

My questions are

1) Is it OK to use these charge values?

2) If not, what would be the solution? I think about putting imaginary atoms on the top of surface atoms based on bulk symmetry but due to surface reconstruction, I am not sure whether that trick works or not.

Thank you for your help in advance.

CW

# X Y Z CHARGE MIN DIST ATOMIC VOL
--------------------------------------------------------------------------------
1 0.1248 3.1763 0.1741 9.0066 1.1837 39.6771 <-
2 2.7213 5.3785 3.9854 8.9218 1.2081 17.7819
3 0.0568 2.5478 3.9854 8.9218 1.2081 17.7817
4 2.6533 0.3456 0.1741 9.0066 1.1838 39.7266 <-
5 5.5015 3.0828 7.9011 8.9175 1.2180 17.7230
6 2.7234 5.4093 11.8186 8.9175 1.2180 17.7230
7 0.0547 2.5786 11.8186 8.9175 1.2180 17.7230
8 2.8328 0.2521 7.9011 8.9175 1.2180 17.7230
9 5.4994 3.1136 15.7344 8.9218 1.2081 17.7817
10 2.9029 5.3158 19.5456 9.0066 1.1837 39.7257 <-
11 5.4314 2.4851 19.5456 9.0066 1.1838 39.6754 <-
12 2.8349 0.2829 15.7344 8.9218 1.2081 17.7819
13 5.4908 0.0258 1.9689 12.4612 0.8980 8.3808
14 2.8435 2.8565 1.9689 12.4611 0.8980 8.3806
15 5.5546 5.6506 5.9318 12.3762 0.9065 8.0356
16 0.0000 0.0000 9.8599 12.3621 0.9071 7.9742
17 2.7797 2.8199 5.9318 12.3762 0.9065 8.0358
18 2.7781 2.8307 9.8599 12.3621 0.9071 7.9746
19 0.0016 0.0108 13.7879 12.3762 0.9065 8.0356
20 0.0654 5.6356 17.7509 12.4612 0.8980 8.3808
21 2.7765 2.8415 13.7879 12.3762 0.9065 8.0358
22 2.7127 2.8049 17.7509 12.4611 0.8980 8.3806
23 1.1616 4.0053 5.5395 7.2604 0.9587 12.1104
24 1.6691 1.1272 2.2026 7.2722 0.9705 12.0089
25 4.4498 1.6998 1.5584 7.2608 0.9371 12.2850
26 1.6165 1.1746 5.5395 7.2604 0.9587 12.1102
27 3.8845 4.5305 1.5584 7.2608 0.9371 12.2848
28 1.1090 3.9579 2.2026 7.2722 0.9705 12.0093
29 0.4277 5.4793 41.2106 7.3213 0.9883 145.2288 <-
30 3.2399 2.9416 3.9135 7.2528 0.9555 12.3012
31 5.0945 0.1109 3.9135 7.2528 0.9555 12.3012
32 2.3504 2.6486 41.2106 7.3212 0.9883 144.6325 <-
33 3.9234 4.4955 6.2384 7.2600 0.9515 12.1430
34 1.1453 3.9966 13.4813 7.2600 0.9515 12.1430
35 1.6119 1.1809 10.2018 7.2583 0.9499 12.1014
36 4.3900 1.6498 9.5179 7.2583 0.9499 12.1022
37 1.6328 1.1659 13.4813 7.2600 0.9515 12.1430
38 4.4109 1.6648 6.2384 7.2600 0.9515 12.1430
39 3.9443 4.4805 9.5179 7.2583 0.9498 12.1020
40 1.1662 4.0116 10.2018 7.2583 0.9499 12.1016
41 0.4604 5.5389 7.8809 7.2501 0.9612 12.1700
42 3.2385 2.9532 11.8388 7.2501 0.9612 12.1698
43 5.0958 0.1225 11.8388 7.2501 0.9612 12.1698
44 2.3177 2.7082 7.8809 7.2501 0.9612 12.1700
45 3.9397 4.4868 14.1803 7.2604 0.9586 12.1102
46 1.6717 1.1309 18.1614 7.2608 0.9371 12.2848
47 4.4472 1.7035 17.5171 7.2722 0.9706 12.0093
48 4.3946 1.6561 14.1803 7.2604 0.9587 12.1104
49 3.8871 4.5342 17.5171 7.2722 0.9705 12.0089
50 1.1064 3.9616 18.1614 7.2608 0.9371 12.2852
51 0.4618 5.5505 15.8063 7.2528 0.9556 12.3012
52 3.2058 3.0128 19.9206 7.3212 0.9883 144.6354 <-
53 5.1285 0.1821 19.9206 7.3213 0.9884 145.2185 <-
54 2.3163 2.7198 15.8063 7.2528 0.9556 12.3012
--------------------------------------------------------------------------------
NUMBER OF ELECTRONS: 464.00000

[graeme]

This is just fine. All space is partitioned into atomic volumes so that a large amount of vacuum is being associated with the surface atoms. Although the volumes of the atomic regions are calculated, they are not necessarily relevant (as in your case).

[cwandtj]

Thank you for your reply.

Even though the large volume of surface atoms, the charge from Bader analysis is OK if we assume that NG*F values are large enough? I am sure but If charge values influenced by each atom's volume, I think that large volume of surface atoms "may" influence the charge values of surface atoms. Feel free to correct me if I am wrong. :)

[graeme]

yes