CCL:G: OPTIMIZATION PROBLEM

From: Cory Pye <cpye||ap.smu.ca>
Subject: CCL:G: OPTIMIZATION PROBLEM
Date: Fri, 4 Nov 2011 16:56:57 -0300 (ADT)
 Sent to CCL by: Cory Pye [cpye**ap.smu.ca]
 Dear Partha,
 You either need to explicitly include the counterions in this 4- complex, and
 maybe also set periodic boundary conditions because you are trying to model a
 solid. I was trying to model the solution phase of a very similar anion with
 zinc instead of cadmium and found that it would also break apart. Another way
 to get around it is to model it as a solute by adding SCRF=CPCM. This may or
 may not work. What you are calculating is a naked gas-phase CdCl6 4- ion which
 most certainly doesn't exist. (Pye, Corbeil, Rudolph, PCCP 8 (2006) p5428)
 -Cory
 On Fri, 4 Nov 2011, partha kundu partha1kundu_+_yahoo.com wrote:
 > Hi,
 I have tried with scf=tight, but it didn't work. What is happening is 4 Cl atom
 is going far apart from each other. But its crystal structure shows it should be
 stable structure.Please help.
 regards.
 Partha
 ________________________________
 > From: partha kundu <partha1kundu() yahoo.com>
 To: CCL Subscribers <chemistry() ccl.net>
 Sent: Friday, 4 November 2011 9:13 AM
 Subject: Re: CCL:G: OPTIMIZATION PROBLEM
 Thank you Bradley for your help. I will try and let you know.
 regards.
 Partha.
 ________________________________
 > From: Bradley Welch bwelch5]![slu.edu <owner-chemistry() ccl.net>
 To: "Kundu, Partha Pratim " <partha1kundu() yahoo.com>
 Sent: Thursday, 3 November 2011 5:57 PM
 Subject: CCL:G: OPTIMIZATION PROBLEM
 Have you tried using scf=tight. Usually scf=qc is used when the standard scf
 calculation fails. 
 Also, have you considered a slightly larger basis set on those chlorines? That
 seems like a very small basis set.
 Bradley Welch 
 On Thu, Nov 3, 2011 at 1:39 AM, Partha p kundu partha1kundu|yahoo.com
 <owner-chemistry-x-ccl.net> wrote:
 >Sent to CCL by: "Partha p kundu" [partha1kundu-*-yahoo.com]
 >Dear All,
 >I have some problem in optimizing a geometry. My input file is the
 following.
 >
 >
 >%chk=cd.chk
 >%mem=200MW
 >%nproc=4
 >#opt b3lyp/gen pseudo=read scf=qc nosym
 >
 >Title Card Required
 >
 > -4 1
 > Cd                -1.05043015   -3.48046330    2.35727072
 > Cl                 0.40206012   -5.72017854    2.49396286
 > Cl                 1.00016821   -2.12566780    2.92423554
 > Cl                -2.50292042   -1.24074806    2.22057858
 > Cl                -0.43020500   -3.31734213   -0.23761836
 > Cl                -1.67065530   -3.64358447    4.95215980
 > Cl                -3.10102851   -4.83525880    1.79030589
 >
 > Cl 0
 > 3-21G
 > ****
 > Cd 0
 > LANL2DZ
 > ****
 >
 > Cd
 > LANL2DZ
 >
 >Last few lines of my output is saying
 >
 >Linear equations converged to 2.037D-10 2.037D-09 after   3 iterations.
 > Search did not lower the energy significantly.
 > No lower point found -- try reversing direction.
 > Search did not lower the energy significantly.
 > No lower point found -- switch to scaled steepest descent.
 > Search did not lower the energy significantly.
 > Scaled steepest descent with Shift=0.000 failed.
 > Search did not lower the energy significantly.
 > Scaled steepest descent with Shift=0.025 failed.
 > Search did not lower the energy significantly.
 > Scaled steepest descent with Shift=0.050 failed.
 > Search did not lower the energy significantly.
 > Scaled steepest descent with Shift=0.075 failed.
 > Search did not lower the energy significantly.
 > No lower point found -- switch to steepest descent.
 > Search did not lower the energy significantly.
 > No lower point found -- run aborted.
 > Error termination via Lnk1e in C:\G03W\l508.exe at Thu Nov 03 11:48:56
 2011.
 >
 >
 >Please help. Thanks in advance.
 >regards.
 >Partha.>
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 >     http://www.ccl.net/cgi-bin/ccl/send_ccl_message
 >
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 >
 >
    *************    !  Dr. Cory C. Pye
  *****************  !  Associate Professor
 ***   **    **  **  !  Theoretical and Computational Chemistry
 **   *  ****        !  Department of Chemistry, Saint Mary's University
 **      *  *        !  923 Robie Street, Halifax, NS B3H 3C3
 **      *  *        !  cpye_._crux.stmarys.ca   http://apwww.stmarys.ca/~cpye
 ***     *  *    **  !  Ph: (902)-420-5654  FAX:(902)-496-8104
  *****************  !
    *************    !  Les Hartree-Focks (Apologies to Montreal Canadien Fans)