Tight Binding Methods for Metallic Systems - Metallic Systems: A Quantum Chemist's Perspective - page 252

DFTB EHTB

2 4 6 8 10 12 14 16

2 4 6 8 10 12 14 16

Energy (eV)

Energy (eV)

B3LYP/cc-pvdz

2 4 6 8 10 12 14 16

Energy (eV)

FIGURE 8.6 Plot.of.the.square.modulus.of.the.Green's.function.versus.energy.(eV).for.ben-
zene.dithiol..TB.results.produced.by.the.DFTB.and.EHTB.codes.are.shown.along.with.DFT.
results.at.the.B3LYP/cc-pvdz.level.of.theory.

detail.in.the.Green's.function.is.a.consequence.of.the.size.of.the.basis.set..The.most.
detail.is.seen.for.the.cc-pvdz.results.that.used.158.molecular.orbitals..In.contrast,.the.
DFTB.and.EHTB.results.used.38.orbitals.with.a.sp.basis.(not.shown).and.48.when.d.
functions.were.included.

8.6 PARALLELIZATION AND SPARSE MATRIX TECHNIQUES
TB.methodologies.are.attractive.for.many.reasons,.one.of.which.is.that.they.may.
be. evaluated. much. more. rapidly. than. their. ab initio . and. DFT. counterparts. [81].
while.retaining.good.accuracy.through.suitable.parameterization..The.eficiency.
with.which.TB.methods.may.be.applied.leads.naturally.to.applications.in.a.num-
ber. of. areas. including. dynamics. calculations. and. studies. of. large. molecules..