*From*: GUSTAVO LAUREANO COELHO DE MOURA <gustavo.moura|*|ufpe.br>*Subject*: CCL: SV: Looking for a PPP parameter set*Date*: Fri, 25 Jan 2019 19:38:58 -0300 (BRT)

Sent to CCL by: GUSTAVO LAUREANO COELHO DE MOURA [gustavo.moura]~[ufpe.br] Dear CCL Community, Two weeks ago, I sent a message to the list where I inquired about parameters for PPP excited state calculations of organic molecules. So far, I have received only one helpful advice from Jens Spanget-Larsen regarding the choice of the two-center two-electron integral equation (Ohno versus Mataga-Nishimoto). I am still looking for PPP parameters, both one- and two-center integral parameters. I am particularly interested in distance dependent two-center one-electron resonance integrals between first neighbor centers. In a first moment, I would settle for calculating only conjugated hydrocarbons. Therefore, I would be grateful if someone could point for a reference where I can find such a fully self-contained PPP parameter set. Thank you very much in advance. Sincerely yours, Gustavo L.C. Moura ----- Mensagem original ----- De: "GUSTAVO LAUREANO COELHO DE MOURA gustavo.moura ~ ufpe.br" <owner-chemistry!^!ccl.net> Para: "Moura, Gustavo L.C. " <gustavo.moura!^!ufpe.br> Enviadas: Sábado, 12 de janeiro de 2019 20:14:40 Assunto: CCL: SV: Looking for a PPP parameter set Sent to CCL by: GUSTAVO LAUREANO COELHO DE MOURA [gustavo.moura|-|ufpe.br] Dear Jens, Thank you very much for your input. I have been employing a CI approach that includes more than single excitations in the calculations and I have observed that, in agreement with your info, I get better results with the OH equation. Regarding the resonance integrals, I have been using a parameter set that employs a linear relationship between first neighbors bond lengths and beta. I have no plans of going beyond first neighbors for the resonance integrals. In the end, what I am searching is a fully self-contained PPP parameter set. One that does not employ different parameters or equations from different sources. Sincerely yours, Gustavo L.C. Moura ----- Mensagem original ----- De: "Jens Spanget-Larsen spanget^^ruc.dk" <owner-chemistry##ccl.net> Para: "Moura, Gustavo L.C. " <gustavo.moura##ufpe.br> Enviadas: Sábado, 12 de janeiro de 2019 6:42:35 Assunto: CCL: SV: Looking for a PPP parameter set Dear Gustavo! Whether you use MN or OH two-center electron repulsion integrals does not depend so much on the other PPP parameters. The choice depends primarily on the configuration interaction (CI) expansion. If the expansion is limited to singly excited configurations (CIS), the strongly screened MN integrals tend to be adequate. But if you include doubly or higher excited configurations, thereby explicitly introducing terms in electron correlation, the less screened OH integrals are more appropriate. You want to include distance depending resonance integrals (beta's). Let me just mention that if you include resonance integrals between 'non-bonded' centers, thereby abandoning the tight-binding approximation, you break the spirit of the PPP concept. Yours, Jens >--< ------------------------------------------------------ JENS SPANGET-LARSEN Office: +45 4674 2710 Dept. of Science Fax: +45 4674 3011 Roskilde University Mobile: +45 2320 6246 P.O.Box 260 Mail: spanget]|[ruc.dk DK-4000 Roskilde, Denmark Web: thiele.ruc.dk/~spanget ------------------------------------------------------ ________________________________________ Fra: owner-chemistry+spanget==ruc.dk]|[ccl.net [owner-chemistry+spanget==ruc.dk]|[ccl.net] på vegne af Gustavo L.C. Moura gustavo.moura(0)ufpe.br [owner-chemistry]|[ccl.net] Sendt: 12. januar 2019 01:19 Til: Jens Spanget-Larsen Emne: CCL: Looking for a PPP parameter set Sent to CCL by: "Gustavo L.C. Moura" [gustavo.moura^ufpe.br] Dear CCL Community, For the continuation of my studies on excited states of organic molecules, I have been looking for a set of Pariser-Parr-Pople parameters. I have already searched on Google and, so far, have not found a PPP parameter set that suits my needs. My main problem is with the two-center part of the Hamiltonian. First, I found out that the choice between the Ohno (OH) or the Mataga-Nishimoto (MN) equations for gamma affect my results a lot. Therefore, I need a parameter set where the choice between OH or MN equations has already been made. Second, I would like to have resonance integrals that depend on the distance between the atoms (not a constant as I have found in some places). I will be very grateful if someone out there points me in the right direction. Sincerely yours, Gustavo L.C. Mourahttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt--_000_A94E15A372E6194CA8719D62642F674401374B5E80MBX2adrucdk_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <html dir="ltr"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style id="owaParaStyle" type="text/css"></style> </head> <body fpstyle="1" ocsi="0"> <div style="direction: ltr;font-family: Courier New;color: #000000;font-size: 10pt;"> <font face="Courier New" size="2"><br> <div>Dear Gustavo!</div> <div> </div> <div>Whether you use MN or OH two-center electron repulsion integrals does not depend so much on the other PPP parameters. The choice depends primarily on the configuration interaction (CI) expansion. If the expansion is limited to singly excited configurations (CIS), the strongly screened MN integrals tend to be adequate. But if you include doubly or higher excited configurations, thereby explicitly introducing terms in electron correlation, the less screened OH integrals are more appropriate. </div> <div><br> </div> <div>You want to include distance depending resonance integrals (beta's). Let me just mention that if you include resonance integrals between 'non-bonded' centers, thereby abandoning the tight-binding approximation, you break the spirit of the PPP concept.</div> <div><br> </div> <div>Yours, Jens >--< </div> <div><br> </div> ------------------------------------------------------<br> JENS SPANGET-LARSEN Office: +45 4674 2710<br> Dept. of Science Fax: +45 4674 3011<br> Roskilde University Mobile: +45 2320 6246<br> P.O.Box 260 Mail: spanget]|[ruc.dk<br> DK-4000 Roskilde, Denmark Web: thiele.ruc.dk/~spanget<br> ------------------------------------------------------<br> <br> ________________________________________<br> Fra: owner-chemistry+spanget==ruc.dk]|[ccl.net [owner-chemistry+spanget==ruc.dk]|[ccl.net] p&#229; vegne af Gustavo L.C. Moura gustavo.moura(0)ufpe.br [owner-chemistry]|[ccl.net]<br> Sendt: 12. januar 2019 01:19<br> Til: Jens Spanget-Larsen<br> Emne: CCL: Looking for a PPP parameter set<br> <br> Sent to CCL by: "Gustavo L.C. Moura" [gustavo.moura^ufpe.br]<br> Dear CCL Community,<br> For the continuation of my studies on excited states of organic molecules, I have been looking for a set of Pariser-Parr-Pople parameters.<br> I have already searched on Google and, so far, have not found a PPP parameter set that suits my needs.<br> My main problem is with the two-center part of the Hamiltonian. First, I found out that the choice between the Ohno (OH) or the Mataga-Nishimoto (MN) equations for gamma affect my results a lot. Therefore, I need a parameter set where the choice between OH or MN equations has already been made. Second, I would like to have resonance integrals that depend on the distance between the atoms (not a constant as I have found in some places).<br> I will be very grateful if someone out there points me in the right direction.<br> Sincerely yours,<br> Gustavo L.C. Moura<br> <br> <br> <br<br<br=<br<br> <br<br<br> <br<br<br> <br> Subscribe/Unsubscribe:<br<br> <br<br> <br> Job: http://www.ccl.net/jobs<br<br>; <br<br> <br<br<br> <br<br> <br> </font><br> </div> </body> </htmlhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt