Chemistry Reference
In-Depth Information
[129]..The.kinetic.energy.dependence.of.the.collision-induced.dissociation.(CID).of.
V
n
+
.(
n
.=.2-20).with.xenon.using.a.guided.ion.beam.mass.spectrometer.has.been.mea-
sured.[130]..The.evolution.of.the.electronic.structure.of.V
n
.clusters.has.been.probed.
by.photoelectron.spectroscopy.[131]..The.electronic.structure.of.vanadium.cluster.
anions.was.also.studied.by.photoelectron.spectroscopy.[132].
Different.theoretical.works.[133-141].exist.on.vanadium.clusters,.too..Most.of.them.
are.model.calculations,.and.only.a.few.studies.have.been.performed.with.DFT.methods..
As.far.as.calculations.are.concerned,.the.irst.theoretical.investigation.on.vanadium.
clusters.was.carried.out.by.Salahub.and.Messmer.with.a.spin-polarized.SCF-Xα-SW.
method. [133].. Liu. et. al.. used. SCF. molecular. orbital. theory. and. DFT. to. show. that.
vanadium.could.become.magnetic.if.its.size.and.dimensions.were.constrained.[134]..
Walch.and.Bauschlicher.carried.out.detailed.calculations.for.several.TM.trimers.and.
used.the.results.to.predict.the.character.of.the.vanadium.trimer.[135]..They.expected.
a.strong.3d.orbital.bonding.and.guessed.that.V
3
.should.be.formed.by.the.combination.
of.three.excited.4s
1
.3d
4
.vanadium.atoms..Dreyssé.et.al..investigated.the.antiferromag-
etic.coupling.between.nearest.neighbor.atoms.in.vanadium.clusters.and.slabs.[136]..
With. the. local. spin. density. (LSD). approximation. and. a. Gaussian. orbital. basis. set,.
Lee.and.Callaway.studied.the.electronic.structures.and.the.magnetism.of.V
9
.and.V
15
.
clusters.with.bcc.symmetry.[137,138]..Zhao.et.al..studied.the.structural.and.magnetic.
properties.of.small.vanadium.clusters.in.the.framework.of.tight-binding.theory.[139]..
Grönbeck.and.Rosén.[140].performed.a.density.functional.study.of.small.vanadium.
clusters.in.the.range.from.V
2
.to.V
8
.using.a.gradient-corrected.exchange-correlation.
functional.and.a.triple.zeta.basis.with.polarization.functions..They.predicted.an.acute.
triangle.ground-state.structure.for.the.neutral.vanadium.trimer.
Another.density.functional.study.of.small.neutral.and.cationic.vanadium.clusters.
in.the.range.from.V
2
.to.V
9
.using.a.6-311G.basis.was.performed.by.Wu.and.Ray.[141]..
Contrary.to.the.work.of.Grönbeck.and.Rosén,.they.found.a.quartet.ground.state.with.
an.apex.angle.of.66°.for.the.neutral.vanadium.trimer.and.a.close-lying.equilateral.
triangle.doublet.excited.state.[142]..From.their.vanadium.dimer.calculations,.Wu.and.
Ray.also.conclude.that.the.results.are.quite.sensitive.to.the.choices.of.the.basis.and.
the.exchange-correlation.functional.
This.brief.summary.shows.the.uncertainties.in.the.determination.of.the.ground-
state.structures.of.small.TM.clusters.based.only.on.calculations..Over.the.last.few.
years,.we.have.performed.several.combined.theoretical.and.experimental.studies.on.
the.determination.of.ground-state.structures.of.different.small.free.TM.clusters.such.
as. the. V
3
. cluster. [143],. small. copper. clusters. [105,144,145],. and. small. nickel. [146].
clusters..The.main.results.we.obtained.are.now.briely.reviewed.
The.neutral.and.cationic.vanadium.trimers.were.optimized.with.a.DFT.method.
[143].. The. GGA. of. Perdew. and. Wang. (PW86). [147]. and. Perdew. (P86). [148,149].
in. conjunction. with. the. local. exchange-correlation. proposed. by. Vosko,. Wilk,. and.
Nusair.(VWN).[150].has.been.used..A.newly.developed.DZVP.basis.set.optimized.
for.gradient-corrected.functionals.[47,48].was.used.for.the.vanadium.atom..We.have.
optimized. this. kind. of. basis. set. for. all. 3d. TM. elements.. Compared. to. the. DZVP.
basis. set. optimized. for. local. functionals,. the. new. basis. set. improves. the. accuracy.
of. the. low-lying. atomic. energy. levels. of. the. 3d. TM. atoms. [48].. We. have. named.
these.new.basis.sets.as.DZVP-GGA.[47]..They.are.available.in.the.basis.set.ile.of.
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