Subject: Molecular B3LYP gaps

From: Stuart Purdie <[email-masked]>
Date: Wed, 3 Jul 2002 19:30:56 +0100 (BST)

Dear CCLers

We've been using the B3LYP hybrid functional for solid state calculations
(as implemented in Crystal98), and we've found a material where is appears
to give incorrect band gaps.  To date, we've only found one report of this
in the literature, namely for FeS2 (J Muscat et al, ChemPhysLett 342
p397-401 (2001)). 

However, given that B3LYP was 'conditioned' on data for molecular systems,
we were wondering if anyone was aware of a case where it gets the
HOMO-LUMO gap incorrect for a molecular system, and what the nature of the
molecular orbitals are that straddle the gap.

I'll post a summary of responses.

Stuart Purdie
PhD student
University of St Andrews
School of Chemistry
Purdie Building
St Andrews
KY16 9SS
+44 (0)1334 463899