From owner-chemistry |-at-| ccl.net Wed Feb 4 23:51:02 2009 From: "Sue Lam chsue2004#,#yahoo.com" <owner-chemistry**server.ccl.net> To: CCL Subject: CCL:G: Broken Symmetry Singlet Excited State Message-Id: <-38555-090204224142-10972-7LRjA6x37X9Brs2cSjYLPg**server.ccl.net> X-Original-From: Sue Lam <chsue2004|,|yahoo.com> Content-Type: multipart/alternative; boundary="0-712308165-1233801683=:21903" Date: Wed, 4 Feb 2009 18:41:23 -0800 (PST) MIME-Version: 1.0 Sent to CCL by: Sue Lam [chsue2004**yahoo.com] --0-712308165-1233801683=:21903 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Hello Chris, =A0 Thank you very much for your reply. I am studying a reaction, in which the = transition state=A0contain biradical character. I=A0have tired=A0to extract= the energy of the pure singlet from the broken symmetry state by using the= spin-correction procedure which was proposed by Yamaguchi et al (Chem. Phy= s. Lett. 1994, 231, 25=9633) =A0 E(singlet) =3D E(broken symmetry from UDFT) + fSC[E(broken symmetry from UD= FT =96 E(triplet from UDFT)) =A0 Where fSC =3D 1<S^2> / [3<S^2> - 1<S^2>] =A0 S^2: expectation value of the total spin =A0 The S^2 before and after the annihilation are listed in the Gaussian output= . In my case,=20 =A0 Annihilation of the first spin contaminant: S^2 before annihilation=A0=A0=A0=A0 0.8631,=A0=A0 after=A0=A0=A0=A0 0.4136 =A0 I am not sure that whether I should use the S^2 before or after the annihil= ation for the projection method.=20 =A0 Best regards, Sue --- On Wed, 2/4/09, Cristian V. Diaconu cvdiaconu!A!rice.edu <owner-chemist= ry]|[ccl.net> wrote: > From: Cristian V. Diaconu cvdiaconu!A!rice.edu <owner-chemistry]|[ccl.net> Subject: CCL:G: Broken Symmetry Singlet Excited State To: "L, Sue " <chsue2004]|[yahoo.com> Date: Wednesday, February 4, 2009, 2:15 PM Sent to CCL by: "Cristian V. Diaconu" [cvdiaconu~!~rice.edu] Hello Sue, The total energy reported by Gaussian is not for 'annihilated' wave function, but for the single determinant that it uses in the Kohn-Sham sche= me (for DFT there isn't really any wave function). There are ways to extract the energy of the pure singlet from the broken symmetry state, but for DFT = they only work in certain cases. Please look at discussions in: J. Chem. Phys. 121, 10026 (2004) J. Chem. Phys. 74, 5737 (1981) Coord. Chem. Rev. 238=96239, 187 (2003) C. J. Cramer, in Essentials of Computational Chemistry. Theories and Models= . (Wiley, Chichester, 2002), Chap. 14.4, pp. 456 =96 459. For example, for a molecule with two unpaired electrons on two sites which interact weakly (e.g., H2 molecule stretched, with a large bond length, say= 10 Angstroms), if <S^2> ~ 1, E(singlet) =3D 2 E(broken sym) - E(triplet) I hope this helps. If you have further questions, please include a little detail on the system you are looking at. Best regards, Chris Sue L chsue2004(~)yahoo.com wrote: > Sent to CCL by: "Sue L" [chsue2004..yahoo.com] > Hi,=20 > I am running a DFT open-shell singlet calculation using Gaussian 03 to obtain a broken symmetry singlet excited state. Does anyone know whether th= e electronic energy calculated at the end based on the annihilated wave funct= ion or not?=20 > Thank you very much! >=20 > Best regards, > Sue>=20 >=20 >=20 -- Cristian V. Diaconu Postdoctoral Research Associate Department of Chemistry - MS60 Rice University PO Box 1892 Houston, TX 77251-1892 Phone: 713-348-3734 Email: cvdiaconu-x-rice.edu -=3D This is automatically added to each message by the mailing script =3D-http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt=0A=0A=0A --0-712308165-1233801683=:21903 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable <table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D"= top" style=3D"font: inherit;"><P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm= 0pt"><FONT face=3D"Times New Roman" size=3D3>Hello Chris,</FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt"><?xml:namespace prefix = =3D o ns =3D "urn:schemas-microsoft-com:office:office" /><o:p><FONT face=3D= "Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT size=3D3><FONT face=3D"Times New Roman">Thank you very much for = your reply. I am studying a reaction, in which the transition state co= ntain biradical character. I have tired to extract the energy of = the pure singlet from the broken symmetry state by using the spin-correctio= n procedure which was proposed by Yamaguchi et al (<I>Chem. Phys. Lett. </I= ><B>1994</B>, <I>231</I>, 25=9633)<I><o:p></o:p></I></FONT></FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>E(singlet) =3D E(broken symmet= ry from UDFT) + fSC[E(broken symmetry from UDFT =96 E(triplet from UDFT))</= FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>Where fSC =3D 1<S^2> / [= 3<S^2> - 1<S^2>]</FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>S^2: expectation value of the = total spin</FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>The S^2 before and after the a= nnihilation are listed in the Gaussian output. In my case, </FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT size=3D3><FONT face=3D"Times New Roman"></FONT></FONT> </DI= V> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT size=3D3><FONT face=3D"Times New Roman">Annihilation of the firs= t spin contaminant:<o:p></o:p></FONT></FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>S^2 before annihilation<SPAN s= tyle=3D"mso-spacerun: yes"> </SPAN>0.8631,<SPAN sty= le=3D"mso-spacerun: yes"> </SPAN>after<SPAN style=3D"mso-spacer= un: yes"> </SPAN>0.4136</FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>I am not sure that whether I s= hould use the S^2 before or after the annihilation for the projection metho= d. </FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><o:p><FONT face=3D"Times New Roman" size=3D3> </FONT></o:p></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>Best regards,</FONT></DIV> <P class=3DMsoNormal style=3D"MARGIN: 0cm 0cm 0pt; mso-layout-grid-align: n= one"><FONT face=3D"Times New Roman" size=3D3>Sue</FONT></DIV><BR><BR>--- On= <B>Wed, 2/4/09, Cristian V. Diaconu cvdiaconu!A!rice.edu <I><owner-chem= istry]|[ccl.net></I></B> wrote:<BR> <BLOCKQUOTE style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: rgb(= 16,16,255) 2px solid">From: Cristian V. Diaconu cvdiaconu!A!rice.edu <ow= ner-chemistry]|[ccl.net><BR>Subject: CCL:G: Broken Symmetry Singlet Excite= d State<BR>To: "L, Sue " <chsue2004]|[yahoo.com><BR>Date: Wedne= sday, February 4, 2009, 2:15 PM<BR><BR><PRE>Sent to CCL by: "Cristian V. Di= aconu" [cvdiaconu~!~rice.edu] Hello Sue, The total energy reported by Gaussian is not for 'annihilated' wave function, but for the single determinant that it uses in the Kohn-Sham sche= me (for DFT there isn't really any wave function). There are ways to extract the energy of the pure singlet from the broken symmetry state, but for DFT = they only work in certain cases. Please look at discussions in: J. Chem. Phys. 121, 10026 (2004) J. Chem. Phys. 74, 5737 (1981) Coord. Chem. Rev. 238=96239, 187 (2003) C. J. Cramer, in Essentials of Computational Chemistry. Theories and Models= . (Wiley, Chichester, 2002), Chap. 14.4, pp. 456 =96 459. For example, for a molecule with two unpaired electrons on two sites which interact weakly (e.g., H2 molecule stretched, with a large bond length, say= 10 Angstroms), if <S^2> ~ 1, E(singlet) =3D 2 E(broken sym) - E(triplet) I hope this helps. If you have further questions, please include a little detail on the system you are looking at. Best regards, Chris Sue L chsue2004(~)yahoo.com wrote: > Sent to CCL by: "Sue L" [chsue2004..yahoo.com] > Hi,=20 > I am running a DFT open-shell singlet calculation using Gaussian 03 to obtain a broken symmetry singlet excited state. Does anyone know whether th= e electronic energy calculated at the end based on the annihilated wave funct= ion or not?=20 > Thank you very much! >=20 > Best regards, > Sue>=20 >=20 >=20 -- Cristian V. Diaconu Postdoctoral Research Associate Department of Chemistry - MS60 Rice University PO Box 1892 Houston, TX 77251-1892 Phone: 713-348-3734 Email: cvdiaconu-x-rice.edu -=3D This is automatically added to each message by the mailing script =3D-http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt</PRE></BLOCKQUOTE></td></tr></table><br>=0A=0A --0-712308165-1233801683=:21903--