Chemistry Reference
In-Depth Information
TABLE 9.3
Binding Energies (
D
0
), Adiabatic
Ionization Potentials (IP), and
Adiabatic Electronic Afinities
(EA) (in kJ/mol) for Small Iron
Clusters Calculated with PP86
Calculated
Experimental
D
0
Fe-Fe
189
114
Fe
2
-Fe
192
184
Fe
3
-Fe
248
211
Fe
+
-Fe
299
268
275
169
Fe
+
-Fe
274
216
Fe
+
-Fe
Fe
−
-Fe
183
183.±.9
Fe
2
−
-Fe
253
235
297
245
Fe
3
−
-Fe
IP
Fe
814
762.±.1
Fe
2
689
608.±.1
Fe
3
606
622.±.5
Fe
4
598
618.±.10
EA
Fe
115
14.6.±.0.3
Fe
2
113
87.0.±.0.8
Fe
3
173
138.±.6
Fe
4
203
172.±.6
Source:
. Salahub,.D..et.al.,.
Phys. Rev. B
,.66,.
155425,.2002..With.permission.
acetylene. molecules. must. come. together. to. form. benzene,. the. subject. of. the. third.
paper.[218].
A.very.large.number.of.calculations.had.to.be.performed.in.order.to.explore.the.
binding.of.acetylene.or.vinylidene.in.the.various.local.minima.that.result,.for.all.of.the.
low-lying.(<50.kJ/mol).states.of.the.clusters..Figure.9.30.shows.the.starting.geometries.
Figure.9.31.shows.the.various.low-lying.structures.found.for.the.4-atom.clusters.
along.with.their.relative.energies.and.the.number.of.unpaired.spins.
Note.that.for.the.positive.clusters,.the.lowest.vinylidene.structure.is.about.25.kJ/
mol.above.the.ground.state..Moreover,.we.have.calculated.the.transition.states.for.
isomerization.of.acetylene.to.vinylidene.in.the.gas.phase.and.on.the.clusters.(using.
Gaussian94. to. locate. the. transition. states. and. ix. their. geometries,. followed. by.
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