Density Functional Calculations of Metal Clusters: Structure, Dynamics, and Reactivity - Metallic Systems: A Quantum Chemist's Perspective - page 302

50.0

45.0

40.0

35.0

30.0

25.0

20.0

15.0

2 3 4 5 6

Cluster size

7 8 9 10

FIGURE 9.12 Binding. energies. per. atom. (kcal/mol). for. neutral. copper. clusters.. Circles,.
calculated;. squares,. experiment. with. anionic. clusters;. triangles,. experiment. with. cationic.
clusters.

anionic.[157].and.cationic.[158].copper.clusters.using.electron.afinities.or.threshold.
detachment. energies. [159]. and. ionization. potentials. [160-163]. from. the. literature..
In.Figure.9.12,.the.derived.binding.energies.from.the.CID.of.anionic.(squares).and.
cationic.(triangles).copper.clusters.are.compared.with.our.calculated.values.(circles).
As. Figure. 9.12. shows,. our. calculated. values. are. in. better. agreement. with. the.
experimental.values.of.the.anionic.copper.cluster.[157].than.with.those.of.the.cat-
ionic.systems.[158].
Among.the.homonuclear.3d.TM.clusters,.Ni.systems.have.received.considerable.
attention.both.experimentally.and.theoretically..It.is.not.our.purpose.here.to.review.
the.corresponding.literature..We.point.the.interested.reader.to.references.[146].and.
[164-181]..In.particular,.the.localized.behavior.of.the.unilled.3d.electrons.in.nickel.
aggregates.results.in.a.great.complexity.of.the.electronic.structure,.which.has.moti-
vated.many.groups.to.study.this.effect.and.its.inluence.on.the.system.properties..As.
a.result,.nickel.clusters.have.constituted.one.of.the.most.studied.clusters.since.they.
are.excellent.systems.for.exploring.new.theoretical.approaches.[146,167-181].
However,. despite.the.availability.of.a.large.number.of.articles.on.small.neutral.
nickel.clusters,.much.less.attention.has.been.paid.to.the.study.of.structures.and.prop-
erties.of.their.corresponding.cationic.and.anionic.systems..Most.DFT.calculations.
on.small.nickel.clusters.have.been.performed.using.basis.sets.optimized.for.the.local.
level. of. theory.. In. Ref.. [146],. a. particular. effort. was. made. to. answer. some. of. the.
questions. related. to. the. lack. of. experimental. information. about. the. structure. and.
electronic. properties. of. small. cationic. and. anionic. nickel. clusters. up. to. the. pen-
tamer..For.this.purpose,.newly.GGA-optimized.basis.sets.for.the.nickel.atom.were.
employed.and.the.most.extensive.theoretical.investigation.performed.on.the.ground.
and.low-lying.states.of.the.neutral,.cationic,.and.anionic.Ni n .clusters.up.to.the.hep-
tamer.was.reported..For.this.study,.different.topologies.and.spin.multiplicities.were.
considered.in.order.to.scan.as.much.of.each.PES.as.possible.and.to.ind.the.lowest.
energetic.structures..The.stability.of.the.structures.with.respect.to.geometrical.dis-
tortions. was. conirmed. by. a. frequency. analysis.. Structural. parameters,. harmonic.
frequencies,.binding.energy,.ionization.potential,.and.electron.afinity.were.reported.