From owner-chemistry /at\ccl.net Tue Mar 28 18:02:00 2006
From: "A ron Vandeputte Aaron.Vandeputte_+_Ugent.be" <owner-chemistry(_)server.ccl.net>
To: CCL
Subject: CCL:G: Reaction path following with Gaussian
Message-Id: <-31348-060328023538-14793-LNCNgr0bDlYURJXp41Dztw(_)server.ccl.net>
X-Original-From: "A  ron  Vandeputte" <Aaron.Vandeputte,Ugent.be>
Date: Tue, 28 Mar 2006 02:35:34 -0500


Sent to CCL by: "A  ron  Vandeputte" [Aaron.Vandeputte ~~ Ugent.be]

In order to calculate tunneling corrections for H-abstractions, I'm trying to calculate the Hessian along the reaction path of the H-abstraction CH3 + CH4 -> CH4 + CH3 with g03

However, if I use as input line

IRC(b3lyp/cbsb7,calcall,Cartesian,StepSize=1,MaxPoints=150,MaxCyc=50,verytight,forward) int=ultrafine nosymm

calcultions fail to converge after 28 points. Gaussian iterates in cycles and the same sequence of energies is calculated till the maximum number of steps is exceeded.

If I use calcfc in stead of calcall, g03 has no trouble to converge but then I don't get the wanted Hessian.

I would be very grateful if someone could help me with my problem.
Aron