Computational Investigations of Metal Oxide Surfaces - Metallic Systems: A Quantum Chemist's Perspective - page 216

interatomic. forces. calculated. “on. the. ly”. from. DFT. calculations,. is. one. approach.
for.studying.processes.at.inite.temperatures.with.reactive.bond-breaking.and.bond-
forming. 140-147 .Hybrid.quantum.mechanics/molecular.mechanics.methods, 148 .which.
treat.the.electronically.important.part.of.the.system.with.quantum.mechanics.and.the.
rest.with.classical.mechanics,.have.also.been.used.to.bridge.length.and.time.scales.in.
modeling.metal.oxide.surface.structure.and.reactivity. 149
A.recent.review.by.Hafner.details.some.of.the.state.of.the.art.in.DFT.and.post-
DFT. methods. 150 . Pacchioni. describes. the. challenges. of. addressing. defective. oxide.
materials.due.to.the.problem.of.self-interaction.in.traditional.DFT.calculations..He.
shows.that.hybrid.functionals.and.DFT+U.approaches.are.offering.alternative.ways.
to.correct.this.issue.and.to.approach.such.important.problems. 151 .Huang.and.Carter.
discuss.recent.advances.in.treating.electron.correlation.by.embedding.coniguration.
interaction.or.other.calculations.in.DFT.calculations.of.solids.and.surfaces. 152 .Held.
provides.another.review.of.improving.electron.correlation.through.adding.a.dynami-
cal.mean.ield.approach.to.a.local.density.approximation.DFT.calculation. 153
Multiscale.modeling.involves.methods.of.bridging.orders.of.magnitude.in.length.
and.time.that.would.otherwise.be.prohibitive.in.the.straightforward.application.of.
electronic.structure.methods..Most.traditional.electronic.structure.applications.are.
limited.to.system.sizes.on.the.order.of.1000.unique.atoms.or.less..Order. N .methods.
might.increase.this.by.a.few.orders.of.magnitude,.but.to.address.macroscopic.length.
scales,. multiscale. methods. are. necessary.. Thus,. multiscale. methods. that. include.
quantum.mechanical.effects.to.understand.materials.remain.an.active.area.of.devel-
opment. 154-159 . Similarly,. to. address. reactions. occurring. over. time. frames. that. are.
prohibitively.long.for.straightforward.dynamics,.or.to.address.many.reaction.events,.
techniques. such. as. kinetic. Monte. Carlo. may. provide. the. answer.. These. are. active.
areas.of.research.that.show.promise.in.opening.applications.to.much.more.complex.
systems.and.materials.properties.beyond.many.of.those.highlighted.in.this.chapter.

ACKNOWLEDGMENTS
The. authors. gratefully. acknowledge. students. Alexandria. Cassady,. Jennie. Cook-
Kollars,. Nathan. Fine,. and. Brent. Sherman. for. research. assistance. related. to. this.
manuscript.

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