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\a/ruc.dk
 DK-4000 Roskilde, Denmark  Web: thiele.ruc.dk/~spanget
 ------------------------------------------------------
 ________________________________________
 Fra: owner-chemistry+spanget==ruc.dk\a/ccl.net
 [owner-chemistry+spanget==ruc.dk\a/ccl.net] p&#229; vegne af Gustavo L.C.
 Moura gustavo.moura(0)ufpe.br [owner-chemistry\a/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. Moura
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 <div>Dear Gustavo!</div>
 <div>&nbsp;&nbsp;</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.&nbsp;</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 &gt;--&lt; &nbsp;</div>
 <div><br>
 </div>
 ------------------------------------------------------<br>
 JENS SPANGET-LARSEN &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
 &nbsp;&nbsp; Office: &#43;45 4674 2710<br>
 Dept. of Science &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
 &nbsp; &nbsp; &nbsp; Fax: &#43;45 4674 3011<br>
 Roskilde University &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
 &nbsp;&nbsp; Mobile: &#43;45 2320 6246<br>
 P.O.Box 260 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
 &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Mail:
 spanget\a/ruc.dk<br>
 DK-4000 Roskilde, Denmark&nbsp; Web: thiele.ruc.dk/~spanget<br>
 ------------------------------------------------------<br>
 <br>
 ________________________________________<br>
 Fra: owner-chemistry&#43;spanget==ruc.dk\a/ccl.net
 [owner-chemistry&#43;spanget==ruc.dk\a/ccl.net] p&amp;#229; vegne af
 Gustavo L.C. Moura gustavo.moura(0)ufpe.br [owner-chemistry\a/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: &quot;Gustavo L.C. Moura&quot;
 [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>
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