Structure of Liquid Metal Surfaces: A First Principles Perspective - Metallic Systems: A Quantum Chemist's Perspective - page 154

2.6

2.4

2.2

2.0

1.8

0 5 10 15 20 0 5 10 15 20

(a) z (Å) (b) z (Å)

6.0

3.0

0.0

-3.0

0 10 20

5 15

(c) z (Å)

0.3

0.2

0.1

0.0

-0.1

-0.2

-0.3

0 5 10 15 20

(d) z (Å)

FIGURE 5.11 (See color insert.) Friedel.oscillations.observed.in.snapshots.from.a.bulk.
liquid.simulation.[73]..Panel.(a).shows.the.valence.charge.densities.for.the.various.MD.time.
steps.taken.from.the.bulk.liquid.simulation..Panel.(b).shows.the.valence.charge.densities.for.
the.same.MD.snapshots.after.a.vacuum.region.has.been.added.to.each.of.the.unit.cells..Panel.
(c).shows.the.valence.charge.density.redistributions.upon.surface.formation.for.the.set.of.bulk.
MD.time.steps..Panel.(d).shows.the.differences.in.the.forces.acting.on.atoms.(i.e.,.the.forces.
induced.by.formation.of.a.surface)..(Adapted.from.Walker,.B.G..et.al.,. J. Chem. Phys .,.124,.
174702,.copyright.2006;.Walker,.B.G..et.al.,. J. Phys. Condens. Matter ,.18,.L269,.copyright.
2006..With.permission.)

in.the.liquid.+.ixed-layer.simulations.in.the.absence.of.Friedel.oscillations.[73],.it.is.
very.unlikely.that.Friedel.oscillations.are.responsible.for.the.formation.of.layers.at.
liquid.metal.surfaces.

5.4 IN-PLANE ORDERING
In.addition.to.focusing.on.the.arrangement.of.the.atoms.transverse.to.the.surface,.
there.is.the.important.issue.of.ordering.in.the.plane.of.the.surface..Simulations.based.
on.glue.model.potentials.of.supercooled.liquid.Au.[42].indicated.that.there.should.
be. formation. of. a. quasihexatic. phase. within. the. layers. at. the. surface.. In. such. an.