Density Functional Calculations of Metal Clusters: Structure, Dynamics, and Reactivity - Metallic Systems: A Quantum Chemist's Perspective - page 304

Neutral

M = 5

M = 5

2.303

M = 3

2.304

(2.308)

2.182

2.194

(2.309)

[2.270]

M = 3

(2.194) (2.186)

[2.269]

[2.157] [2.154]

2.158

2.240

2.180

(2.111)

2.187

(2.245)

(2.185)

[2.077] (2.194)

[2.213]

[2.155]

[2.156]

Cationic

M = 4

2.281
(2.285)
[2.250]

M = 4 M = 4

2.251
(2.255)
[2.220]

2.227
(2.232)
[2.192]

2.254
(2.258)
[2.220]

M = 4

2.205
(2.113)
[2.165]

2.271
(2.275)
[2.240]

2.250
(2.255)
[2.220]

2.196
(2.201)
[2.163]

Anionic

M = 4

2.332
(2.336)
[2.296]

2.236
(2.402)
[2.360]
2.233
(2.240)
[2.203]

M = 4

M = 6

2.205
(2.205)
[2.170]

2.232
(2.240)
[2.204]

M = 4

2.174
(2.239)
[2.240]

2.225
(2.333)
[2.201]

2.398
(2.237)
[2.204]

2.281
(2.192)
[2.154]

FIGURE 9.14 Ground-state.structures,.bond.lengths.(in.Å),.and.multiplicities.of.Ni n ,. Ni n + ,.
and. Ni n − .( n .=.2-5).clusters..The.original.DZVP-LDA.basis.set.as.well.as.the.newly.developed.
DZVP-GGA,.parentheses,.and.TZVP-GGA,.square.brackets,.basis.sets.in.combination.with.
the. VWN. functional. were. employed.. (Reprinted. from. Lopez. Arvizu,. G.. et. al.,. J. Chem.
Phys .,.126(19),.May.21,.194102-1,.2007..With.permission.)

respectively.. The. ground. state. of. the. neutral. trimer. is. formed. by. adding. an. extra.
electron.(indicated.by.a.dotted.arrow).to.the.singly.occupied.antibonding.42.MO.of.
the.cationic.trimer.(left.side.of.Figure.9.16)..This.orbital.results.in.the.doubly.occu-
pied.40.MO.of.the.neutral.system.(right.side.of.Figure.9.16)..The.crossing.of.differ-
ent.MOs.(indicated.by.dashed.arrows).occurs,.and.the.two.unpaired.electrons.of.the.
neutral.Ni 3 .ground.state.occupy.the.42.and.43.MOs.(Figure.9.16).
On.the.other.hand,.the.anionic.trimer.ground.state.is.formed.by.adding.an.extra.
electron.to.the.singly.occupied.42.MO.of.the.neutral.system.(Figure.9.17)..The.cross-
ing.of.several.MOs.occurs.in.this.case,.too.(Figure.9.17)..The.three.unpaired.elec-
trons.occupy.the.MOs.42,.43,.and.44.in.the.anionic.trimer.(Figure.9.17).
The. VWN. calculations. predict. the. bipyramidal. structure. on. the. quintet. PES.
as.the.ground-state.structure.for.the.neutral.nickel.pentamer..This.structure.is.fol-
lowed.by.a.pyramidal.structure.on.the.septet.PES..With.the.DZVP-GGA/PW86.and.