Hi everyone,
I did a "$pop nbo AO ab atoms 1,2,4" on a system I'm calculating, and find the results confusing.
I'll give you a short example.
*********************
*** Total density ***
*********************
The following atoms are selected
iat= 1
iat= 2
iat= 4
Nr Atom Natural Electron Configuration
--------------------------------------------------
1 se [core] 4s( 1.85) 4p( 5.35) 5p( 0.01) 4d( 0.05)
2 mn [core] 4s( 0.52) 4p( 0.03) 3d( 5.54) 4d( 0.03)
4 mn [core] 4s( 0.52) 4p( 0.03) 3d( 5.55) 4d( 0.03)
NATURAL POPULATIONS: Natural atomic orbital occupancies
NAO Atom # Type(AO) Occupancy
----------------------------------------
[snip]
49 mn 2 s Cor(1s) 2.00000
50 mn 2 s Cor(2s) 2.00000
51 mn 2 s Cor(3s) 1.99919
52 mn 2 s Val(4s) 0.51828
53 mn 2 s Ryd 0.00401
54 mn 2 s Ryd 0.00020
55 mn 2 p Cor(2px) 2.00000
56 mn 2 p Cor(2py) 2.00000
57 mn 2 p Cor(2pz) 2.00000
58 mn 2 p Cor(3px) 1.99911
59 mn 2 p Cor(3py) 1.99911
60 mn 2 p Cor(3pz) 1.99910
61 mn 2 p Ryd 0.01140
62 mn 2 p Ryd 0.01273
63 mn 2 p Ryd 0.00928
64 mn 2 p Ryd 0.00010
65 mn 2 p Ryd 0.00008
66 mn 2 p Ryd 0.00014
67 mn 2 d Val(3dz2) 1.08546
68 mn 2 d Val(3dxz) 1.10647
69 mn 2 d Val(3dyz) 1.15264
70 mn 2 d Val(3dxy) 1.08015
71 mn 2 d Val(3dx2-y2) 1.12018
72 mn 2 d Ryd 0.00349
73 mn 2 d Ryd 0.00589
74 mn 2 d Ryd 0.00528
75 mn 2 d Ryd 0.00691
76 mn 2 d Ryd 0.00816
77 mn 2 d Ryd 0.00030
78 mn 2 d Ryd 0.00027
79 mn 2 d Ryd 0.00031
80 mn 2 d Ryd 0.00026
81 mn 2 d Ryd 0.00025
82 mn 2 d Ryd 0.00001
83 mn 2 d Ryd 0.00001
84 mn 2 d Ryd 0.00001
85 mn 2 d Ryd 0.00001
86 mn 2 d Ryd 0.00001
87 mn 2 f Ryd 0.00001
88 mn 2 f Ryd 0.00002
89 mn 2 f Ryd 0.00001
90 mn 2 f Ryd 0.00001
91 mn 2 f Ryd 0.00001
92 mn 2 f Ryd 0.00001
93 mn 2 f Ryd 0.00002
This is all fine. It's a highspin Mn2+, exactly what I wanted.
Now for the second part:
***********************************
*** Spin density (Dalpha-Dbeta) ***
***********************************
The following atoms are selected
iat= 1
iat= 2
iat= 4
Nr Atom Natural Electron Configuration
--------------------------------------------------
1 se [core]
2 mn [core] 3d( 0.03)
4 mn [core] 3d( 4.29) 4d( 0.01)
NATURAL POPULATIONS: Natural atomic orbital occupancies
NAO Atom # Type(AO) Occupancy
----------------------------------------
[snip]
49 mn 2 s Cor(1s) 0.02547
50 mn 2 s Cor(2s) 0.00084
51 mn 2 s Cor(3s) 0.00000
52 mn 2 s Val(4s) -0.00047
53 mn 2 s Ryd -0.00118
54 mn 2 s Ryd -0.03588
55 mn 2 p Cor(2px) 0.00663
56 mn 2 p Cor(2py) 0.00656
57 mn 2 p Cor(2pz) 0.00623
58 mn 2 p Cor(3px) 0.00001
59 mn 2 p Cor(3py) 0.00002
60 mn 2 p Cor(3pz) -0.00002
61 mn 2 p Ryd -0.00327
62 mn 2 p Ryd -0.00326
63 mn 2 p Ryd -0.00343
64 mn 2 p Ryd -0.06484
65 mn 2 p Ryd -0.06932
66 mn 2 p Ryd ridft ended normally
-0.06802
67 mn 2 d Val(3dz2) 0.00248
68 mn 2 d Val(3dxz) 0.01485
69 mn 2 d Val(3dyz) 0.00415
70 mn 2 d Val(3dxy) 0.00092
71 mn 2 d Val(3dx2-y2) 0.00427
72 mn 2 d Ryd 0.00001
73 mn 2 d Ryd 0.00001
74 mn 2 d Ryd -0.00003
75 mn 2 d Ryd -0.00002
76 mn 2 d Ryd -0.00003
77 mn 2 d Ryd -0.00141
78 mn 2 d Ryd 0.00014
79 mn 2 d Ryd -0.00016
80 mn 2 d Ryd -0.00084
81 mn 2 d Ryd -0.00039
82 mn 2 d Ryd -0.86136
83 mn 2 d Ryd -0.84990
84 mn 2 d Ryd -0.77574
85 mn 2 d Ryd -0.88270
86 mn 2 d Ryd -0.83589
87 mn 2 f Ryd 0.00000
88 mn 2 f Ryd 0.00000
89 mn 2 f Ryd 0.00000
90 mn 2 f Ryd 0.00000
91 mn 2 f Ryd 0.00000
92 mn 2 f Ryd 0.00000
93 mn 2 f Ryd 0.00000
The way I understand it, the Spin Density should either be 0 or close to +1 or -1, but never ever larger than the total density. For my Mn, I expected 0 everywhere, and +1/-1 in the valence d-shells (67-71). But if you have a look at the second quotation, the spin density seems to be located in Ryd orbitals (82-86), where no total density was shown at all.
Either I'm misinterpreting the results, or I've found some kind of weird bug...
Mike
P.S.: A second Mn in my system shows perfectly normal behaviour...
