The PhD proposal concerns the study/optimization of Valence Bond wave functions for excited states. This development will contribute to enlarge the scope of VB computations to new types of electronic systems. Prospect candidates should have a background in theoretical quantum chemistry, good knowledge of English, and enthusiasm for theoretical chemistry and computer applications. Experience with linux and programming languages (fortran, python) is desired. Interested candidates should submit (by e-mail): a CV, grade transcripts, copies of Diploma or Master's certificates and transcripts, short summary of Diploma or Master's thesis, copies of publications (if available) and the names of two referees (with postal and e-mail addresses). Please, include a cover letter with a brief statement why you are interested in the position. Prof. Dr. Stephane Humbel, Aix-Marseille University, F-13013 Marseille, France Email: stephane.humbel@univ-amu.fr www: http://www.ism2.univ-cezanne.fr/ then CTOM group

1. Ecole Doctorale des Sciences Contrats Doctoraux
Chimiques ED250 2013
Web site: http://www.ism2.univ-
Laboratory: iSm2
cezanne.fr
Team: Chimie ThéOrique et Modèles (CTOM) Head of the team: Stéphane HUMBEL
Supervisor: Pr Stéphane HUMBEL Email: stephane.humbel@univ-amu.fr
Title: Valence Bond progresses for charge transfer systems
Scientific field: Quantum Chemistry
Key words: Configuration Interaction - Valence Bond - Charge transfer - Fortran
To be a candidate, contact Stéphane HUMBEL: stephane.humbel@univ-amu.fr +
04-91-28-86-67. Good knowledge in basis quantum chemistry and a pronounced
taste for computer sciences and programming.
The Doctoral School council will audition the best candidates during the 2nd week
of may 2013. This council will take in charge a return ticket by train (2nd class)
from Paris to Marseille. Arrangements with the CTOM team might be made for
the accommodation in Marseille. "Skype auditions" are also possible.
Background, Context:
Major advances in ground state chemistry have benefit from the VB thinking and
actual computations.[1] Among numerous successful stories, Shaik and Pross
diagrams are probably the seed of most significant results about reactivity (from
the simple SN2 reaction, up to oxidations biochemistry). Other major
contributions include π delocalization controversies, the resonance in bonds, odd
electron bonds, charge-shift bonds, Hydrogen bonds, etc … [2] Actual VB
computations require "Non-Orthogonal Configuration Interactions" (NOCI). Over
the past 20 years, these approaches have gained considerable efficiency. One of
the major conceptual advance for accuracy is the "Breathing Orbital VB" (BOVB)
approach by Hiberty et al.[3] Most recent advances concerning the
implementation of VB methods have come from developments proposed and
implemented by Prof Wei Wu (Xiamen University, People's Republic of China).[4]
Our french laboratory has been working since several years on Lewis writing of
wave functions.[5] Among other subjects we developed an education oriented
the JAVA applet HuLiS that computes "Huckel-Lewis wave functions", within the
simple Hückel hamiltonian.[6] The ab-initio version of the Lewis approach has
been successfully applied to a variety of systems, in organic or organometallic
chemistry.[7] Despites these successes on ground state chemistry, seldom work
has been done to variationaly optimize wave functions for excited state.[8]

2. Research subject, work plan:
The PhD proposal concerns the study of Valence
Bond wave functions for excited states. This
development will contribute to enlarge the scope
of VB computations to new types of electronic
systems.
-I- Projected approach for Hartree-Fock and post
HF wavefunctions, already implemented in our lab,
shall be used for applications. These applications
shall concern aromaticity and charge transfer in
general for chemically relevant systems. One of
the interesting information brought by this
projected approach concerns a “trust” parameter
to use to compare projected, the NOCI, and the (a) (b)
delocalized CASSCF-like wave functions. Figure 1 : Modification of the
leading Lewis structure for
-II- Implementation of a method to optimize two configurations. The
Valence Bond wave functions for excited states. highest bi-occupied orbital is
This challenging part targets at adding this changed from (a) to (b). In
functionality to the XMVB2.0 valence Bond (a) it is =C2-C3= anti
program developed by Prof W. Wu in Xiamen bonding, while in (b) it is
University. This work will be made in a large part bonding. Hence, the biradical
in collaboration the Xiamen University group. Here Lewis structure shall be more
again, the trust parameter previously define shall representative of the
be use appraise the optimized VB wave functions electronic distribution in (b)
by comparison to other approaches. than in (a).
Excited states are likely to exhibit a variety of electronic distributions. For some
resonant or localized states, the VB wave functions can be a very good choice,
reconciling accuracy and simplicity. Our approach will make a necessary link
between VB-CI and MO-CI descriptions. Both pure VB and Lewis-like wave
functions will be used.
References:
[1] (a)S. Shaik, P. C. Hiberty, A Chemist’s Guide to Valence Bond Theory, Wiley-Interscience, New
York 2008. (b) We recently co-organised a workshop on VB related theories : B. Braïda, E. Derat,
S. Humbel, P.C Hiberty, S. Shaik ChemPhysChem 13, 4029 (2012)
[2] (a) S. Shaik, A. Shurki, D. Danovich, P.C. Hiberty, Chem. Rev. 101, 1501 (2001). (b) P.C.
Hiberty, S. Humbel, S. Shaik, D. Danovitch, J. Am. Chem. Soc. 117, 9003 (1995). (c) S. Shaik, P.
Maître, G. Sini, P. C. Hiberty, J. Amer. Chem. Soc. 114, 7861 (1992). (d) S. Shaik, D. Danovitch,
W. Wu, P. C. Hiberty, Nature Chemistry. 1, 443 (2009). (e) S. Humbel, J. Phys. Chem. A 106,
5517 (2002). (f) M. Olivucci, I.N. Ragazos, F. Bernardi, M.A. Robb, J. Am. Chem. Soc. 115, 3710
(1993).
[3] (a) P.C. Hiberty, S. Humbel, C. Byrman, J.H. van Lenthe, J. Chem. Phys. 101, 5969 (1994). (b)
P.C. Hiberty, S. Shaik J. Comp. Chem. 28, 137 (2007).
[4] (a) L.C. Song, J.S. Song, Y.R. Mo, W. Wu J. Comp. Chem. 30, 399 (2009). (b) F. Ying, P. Su,
Z. Chen, S. Shaik, W. Wu J. Chem. Theory Comput., 8, 1608 (2012).
[5] M. Linares, B. Braïda, S. Humbel J. Phys. Chem. A 110, 2505 (2006).
[6] (a) http://www.hulis.free.fr (b) Y. Carissan, D. Hagebaum-Reignier, N. Goudard, S. Humbel, J.
Phys. Chem. A. 118, 13256 (2008).
[7] (a) M. Linares, B. Braïda, S. Humbel Farad. Discuss. 135, 273 (2007); (b) M. Linares, S.
Humbel, B. Braïda, J. Phys. Chem. A. 118, 13249 (2008); (c) M. Linares, B. Braïda, S. Humbel
Inorg. Chem 46, 11390 (2007).
[8] See for instance (a) J. Gu, Y. Lin, B. Ma, W. Wu, S. Shaik J. Chem. Theory Comput. 4, 2101
(2008). (b) High spin with D. Danovitch, S. Shaik J. Chem. Theory Comput. 6, 1479 (2010).