From owner-chemistry@ccl.net Thu Aug 16 14:40:00 2007
From: "Cory Pye cpye===crux.smu.ca" <owner-chemistry__server.ccl.net>
To: CCL
Subject: CCL:G: convergence failure with pop=nobread
Message-Id: <-34942-070816103328-2585-m6VWmdFjB/aCbWohtgqdOA__server.ccl.net>
X-Original-From: Cory Pye <cpye^-^crux.smu.ca>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Date: Thu, 16 Aug 2007 10:53:32 -0300 (ADT)
MIME-Version: 1.0


Sent to CCL by: Cory Pye [cpye::crux.smu.ca]
Hi,

I would suggest trying a ROHF/STO-3G, UHF/STO-3G, or maybe a UBLYP or ROBLYP
equivalent first, to get a converged wavefunction. Then use guess=read in the
6-31G(d) calculation to read in the converged wavefunction from the checkpoint
file. If The STO-3G calcs don't converge, then you can use the more robust but
expensive methods (e.g. SCF=QC) at the lower level, and then read that guess in.

-Cory


On Wed, 15 Aug 2007, immanuel feng feng.immanuel/agmail.com wrote:

> Hi, I tried to perform the NBO analysis on the radical cation with
> ROB3LYP/6-311G(d,p) pop=nboread. The structure is some aromatic six-membered
> heterocyclic hydroxyl. the output is here:
>
> SCF Done:  E(ROB+HF-LYP) =  -371.234346792     A.U. after  129 cycles
>              Convg  =    0.9267D-02             -V/T =  2.0100
>              S**2   =   0.7500
>  KE= 3.675742463760D+02 PE=-1.429641058322D+03 EE= 4.027813852709D+02
>  Annihilation of the first spin contaminant:
>  S**2 before annihilation     0.7500,   after     0.7500
>  Convergence failure -- run terminated.
>  Error termination via Lnk1e in /usr/g03/l502.exe at Tue Jun 13 21:57:44
> 2006.
>  Job cpu time:  0 days  0 hours 20 minutes 28.3 seconds.
>  File lengths (MBytes):  RWF=     20 Int=      0 D2E=      0 Chk=      1
> Scr=      1
>
> I've also tried to basis set to 6-31G(d), but convergence was still failure.
> Could anyone give some advice? Thank you!
>

   *************    !  Dr. Cory C. Pye
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