From owner-chemistry@ccl.net Mon Jun 22 02:50:01 2015
From: "Stefan Grimme grimme. a .thch.uni-bonn.de" <owner-chemistry a server.ccl.net>
To: CCL
Subject: CCL: H-bond and dispersion energy
Message-Id: <-51466-150622015949-12032-dUgs6+uhT+480Ayo76rvnA a server.ccl.net>
X-Original-From: "Stefan  Grimme" <grimme,thch.uni-bonn.de>
Date: Mon, 22 Jun 2015 01:59:48 -0400


Sent to CCL by: "Stefan  Grimme" [grimme:+:thch.uni-bonn.de]
>Stefan,
>
>What are your thoughts on D3 vs D3BJ?
>Sam Abrash

Dear Sam,
D3BJ(BJ=Becke-Johnson damping scheme) is our default since 4 years. It
has the physically correct short-range behavior (i.e., the dispersion energy
goes to a constant for small inter-atomic distances) and yields better
structures than D3(0). The interaction energies with both versions are 
very similar. Note that the (non-empirical) dispersion coefficients
are the same in both versions. D3(0) should only be used with
M06... type functionals which already include the medium range part
and for which double-counting effects with B3(BJ) would occur.
Best wishes
Stefan