CCL:G: Reaction path following with Gaussian

From: "A ron Vandeputte" <Aaron.Vandeputte,Ugent.be>
Subject: CCL:G: Reaction path following with Gaussian
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