From owner-chemistry ^%at%^ ccl.net Tue Aug 31 10:04:00 2010 From: "Mahmoud A. A. Ibrahim m.ibrahim_._compchem.net" To: CCL Subject: CCL: gaussian produces lots of imaginary frequencies Message-Id: <-42657-100831033237-7936-22G/Rq5f0xbq5PJ/13cigw%server.ccl.net> X-Original-From: "Mahmoud A. A. Ibrahim" Content-Type: multipart/alternative; boundary=0015175ca7f65602d1048f1995ba Date: Tue, 31 Aug 2010 08:32:29 +0100 MIME-Version: 1.0 Sent to CCL by: "Mahmoud A. A. Ibrahim" [m.ibrahim~!~compchem.net] --0015175ca7f65602d1048f1995ba Content-Type: text/plain; charset=ISO-8859-1 Dear Abhishek and Johannes I am afraid, you have done frequency calculations at level different from the level you have optimized your molecule at. In other words, frequency calculations must be done at the same level of optimization, otherwise it will be meaningless. If it is not the case, we would love to have a look on your molecule. Sincerely; M. Ibrahim On Tue, Aug 31, 2010 at 5:26 AM, ABHISHEK SHAHI shahi.abhishek1984(~) gmail.com wrote: > Dear All > I have similar problem as 'Johannes Salewski ' . I am getting 3 or 4 > or 5 or 6 or sometime 8 negative frequency for water complexes having 6 > atoms only.Some negative Frequencies are quite larger(`2300 cm-1).How to > resolve this problem ? I have tried it for 7-8 times but got nearly same > result. I have chosen #mp2=full/aug-cc-pvtz opt=(maxcycle=100) freq=noraman > nosymm scf=(tight,vshift=150,xqc) route section with enough memory.In output > , Its showing normal termination for both optimization and frequency > calculation with several order saddle point (i.e. more negative > frequencies).I am looking for a proper suggestion. > > your suggestions will appreciated > > > > > > With regards; > *ABHISHEK SHAHI* > IISc bangalore-12 > India > Official E-mail: shahi|*|ipc.iisc.ernet.in > CC: shahi.abhishek1984|*|gmail.com > -- Mahmoud A. A. Ibrahim Current Address 7.05, School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom. Home Address Chemistry Department, Faculty of Science, Minia University, Minia 61519, Egypt. Contact Information Email: m.ibrahim%%compchem.net Website: www.compchem.net Fax No.: +20862342601 --0015175ca7f65602d1048f1995ba Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Dear Abhishek and Johannes
I am afraid, you have done frequency calcula= tions at level different from the level you have optimized your molecule at= . In other words, frequency=A0calculations must be done at the same level o= f optimization, otherwise it will be meaningless.
If it is not the case, we would love to have a look on your molecule.<= /div>
Sincerely;
M. Ibrahim

On Tue, Aug 31, 2010 at 5:26 AM, ABHISHEK SHAHI shahi.abhishek1984(= ~)gmail.com <owner-chemistry%%ccl.net> = wrote:
Dear All
=A0=A0=A0=A0=A0 I have similar= problem as 'Johannes Salew= ski ' . I am getting 3 or 4 or 5 or 6 or sometime 8 negat= ive frequency for water complexes having 6 atoms only.Some negative Frequen= cies are quite larger(`2300 cm-1).How to resolve this problem ? I have trie= d it for 7-8 times but got nearly same result. I have chosen #mp2=3Dfull/au= g-cc-pvtz opt=3D(maxcycle=3D100) freq=3Dnoraman nosymm scf=3D(tight,vshift= =3D150,xqc) route section with enough memory.In output , Its showing normal= termination for both optimization and frequency calculation with several o= rder saddle point (i.e. more negative frequencies).I am looking for a prope= r suggestion.

=A0your suggestions will appreciated





With regards;
= =A0ABHISHEK SHAHI
=A0 IISc bangalore-12
=A0India
=A0 Official E-mail: shahi|*|ipc.iisc.ernet.in=
=A0 CC:=A0 shahi.abhishek1984|*|gmail.com



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=A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 Mahmoud A. A. Ibrahim=A0 =A0 =A0 =A0=A0
=A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 Current Address
=A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0=A0 7.05, School of Chemistry,
=A0 =A0 =A0 =A0 =A0 =A0 =A0 The Un= iversity of Manchester,
=A0 =A0 =A0 =A0=A0 Oxford Road, Manchester, M13 9PL,
=A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 United Kingdom.

=A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 Home Address
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 Chemistry Department,
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 Fa= culty of Science,
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Minia = University,
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 Minia 61519,
=A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Egypt.

= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 Contact Information
=A0 =A0 = =A0 =A0 =A0=A0 Email: m.ibrahim%%c= ompchem.net
=A0 =A0 =A0 =A0 =A0 =A0 =A0 Website: ww= w.compchem.net
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0 Fax No.: +2086= 2342601
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