From owner-chemistry@ccl.net Thu Jun 19 18:00:00 2014 From: "Olasunkanmi Lukman Olawale walecomuk]-[yahoo.co.uk" To: CCL Subject: CCL: Symmetry vs Non-symmetry impostition Message-Id: <-50243-140619124705-4786-W2OYbZhCPGGDsppjaLWivg|*|server.ccl.net> X-Original-From: Olasunkanmi Lukman Olawale Content-Type: multipart/alternative; boundary="862858767-2105263782-1403196417=:76916" Date: Thu, 19 Jun 2014 17:46:57 +0100 MIME-Version: 1.0 Sent to CCL by: Olasunkanmi Lukman Olawale [walecomuk:+:yahoo.co.uk] --862858767-2105263782-1403196417=:76916 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Dear CClers,=0A=0AI have carried out geometry optimizations and frequency c= alculations on some set of heteroaromatic molecules using DFT/B3LYP/6-311G*= * level of theory in G09W. The calculations were done first without symmetr= y constraint and later with symmetry constraint using a specific symmetry p= oint group, which I expect the molecules to adopt. In each case I have got = different energy values (not unexpected) but the results with symmetry impo= sition returned some imaginary frequencies which left me with the conclusio= n that the molecules are not in the ground state upon imposition =A0of such= symmetry. The energy values from symmetry imposed calculations are slightl= y higher than those without symmetry constraint.=0AMy questions are:=0A- is= it not possible to get the ground state configurations of these molecules = at the particular symmetry point group I imposed on them?=0A- can I conclud= e that the geometry with a less order symmetry point group is more stable t= han the more symmetric one (somewhat against the rule of stability!)?=0A=0A= Your contributions will be appreciated.=0AThank you.=0A=0A=A0=0ALukman Olaw= ale Olasunkanmi=0A=0ACurrent Address:=0ADepartment of Chemistry,=0AFaculty = of Agriculture, Science and Technology,=0ANorth West University (Mafikeng C= ampus),=0ASouth Africa.=0ACell: +27710156252 OR +27747614116=0A=0APermanent= Address:=0ADepartment of Chemistry,=0AObafemi Awolowo University,=0AIle-If= e,=0ANigeria.=0ACell: +234 805 240 1564=0A --862858767-2105263782-1403196417=:76916 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Dear CClers,

I have carried out geometry optimizations and freque= ncy calculations on some set of heteroaromatic molecules using DFT/B3LYP/6-= 311G** level of theory in G09W. The calculations were done first without sy= mmetry constraint and later with symmetry constraint using a specific symme= try point group, which I expect the molecules to adopt. In each case I have got different energy values (not unexpected) but the results with sym= metry imposition returned some imaginary frequencies which left me with the= conclusion that the molecules are not in the ground state upon imposition =  of such symmetry. The energy values from symmetry imposed calculation= s are slightly higher than those without symmetry constraint.
<= div style=3D"color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNe= ue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; backgr= ound-color: transparent; font-style: normal;">My questions are:
- is it not pos= sible to get the ground state configurations of these molecules at the part= icular symmetry point group I imposed on them?
- can I conclude that the = geometry with a less order symmetry point group is more stable than the mor= e symmetric one (somewhat against the rule of stability!)?

Your contributions will be appreciated.
Than= k you.

 
Lukman Olawale Olasunkanmi

Current Address:
Department of Chemistry,
Faculty of Agriculture, Science and Technology,
North = West University (Mafikeng Campus),
South Africa.
<= /span>Cell: +27710156252 OR +27747614116

<= /span>Permanent Address:
Dep= artment of Chemistry,
Obafemi Awolowo University,
Ile-Ife,
Nigeria.
Cell: +234 805 240 1564
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