Two PhD Positions Electronic Structure Theory
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Date: Thu Apr 24 05:47:26 2008
Subject: 08.04.24 Two PhD Positions Electronic Structure Theory
POSITION 1: For students having a Masters or equivalent from outside the European Union.
POSITION 2: For students having a Masters or equivalent from a European Union country.
POSITION 1 : Development of New Functionals and Algorithms for
Time-Dependent Density-Functional Theory (TDDFT) and
Implementation in Gaussian- and Wavelet-based Programs
Starting date: September 2008.
Funding: 3 year RTRA scholarship (approximately 1650 Euro gross per month.)
Background: Since its introduction into Quantum Chemistry by one of us over
a decade ago [C95], time-dependent density-functional theory (TDDFT) has
become the dominant single-determinant method for modeling the excited
states of medium and large molecules. (See Ref. [C08] for notes from a
recent course on TDDFT.) As such it is the obvious method for modeling the
spectroscopy of nanoscale systems where it has already been applied to
calculate the optical absorption spectra of fullerenes [BAHK98] and
nanotubes [MRRV03]. The continued success of this technique for treating
the spectroscopy of nanoscale molecules ultimately depends both on
(i) identifying and overcoming weaknesses of the method and (ii) the
continued development of efficient algorithms and programs for carrying
out calculations. The objective of this thesis project is to do both,
with the ultimate aim in mind of applying the improved method to studying
molecular switches, excited states in biomolecules, and/or organic
photovoltaic cells.
Research Project: Problems with conventional TDDFT for photochemical
modeling have been reviewed in Ref. [C01]. One which is particularly
bothersome is the inadequate treatment of two-electron excitations which
is needed if TDDFT is to be used for modeling photochemical reactions
which pass through biradicalod intermediates. It is proposed to pursue
the method of polarization propagator corrections [C05] to gain insight
into how new functionals can be constructed which go beyond the TDDFT
adiabatic approximation to include explicit 2-electron excitations.
This method is already partially implemented in the deMon2k program
[deMon2k], so the first job is to complete and test that implementation.
The familiarity gained from working with TDDFT in a Gaussian-based
Quantum Chemistry code, will next be used to implement Casida's linear
response TDDFT equations [C95] in a wavelet-based code [GDN+06] which
will allow the application of TDDFT to significantly larger and more
complex systems.
The ideal candidate will have completed his/her Masters in Quantum
Chemistry, Theoretical Solid State Physics, or a related field. He or
she should be comfortable with formal methods and have experience in
programming. A condition of the scholarship is that the candidate must
have a Masters degree (or the equivalent) from outside the European Union.
The thesis can be written in English. However it seems normal that the
student will want to learn French while living in France.
References
[C08] Course on TDDFT at the level of 2nd Year Master's in Theoretical Chemistry
[url]http://dcm.ujf-grenoble.fr/PERSONNEL/CT/casida/Enseignement/M2/TDDFT/index.html[/url]
[GDN+06] L. Genovese, T. Deutsch, A. Neelov, S. Goedecker, and G. Beylkin, J. Chem. Phys. 125, 074105 (2006). Efficient solution of Poisson's equation with free boundry conditons
[C05] M.E. Casida, J. Chem. Phys. 122, 054111 (2005). "Propagator Corrections to Adiabatic Time-Dependent Density-Functional Theory Linear Response Theory"
[MRRV03] A.G. Marinopoulos, L. Reining, A. Rubio, and N. Vast, Phys. Rev. Lett. 91, 046402 (2003). Optical and Loss Spectra of Carbon Nanotubes: Depolarization Effects and Intertube Interactions
[C01] M.E. Casida, in Accurate Description of Low-Lying Molecular States and Potential Energy Surfaces, ACS Symposium Series 828, edited by Mark R. Hoffmann and Kenneth G. Dyall (ACS Press: Washington, D.C., 2002), ISBN 0-8412-3792-1, (Proceedings of ACS Symposium, San Diego, Calif., 2001), pp. 199-220. "Jacob's ladder for time-dependent density-functional theory: Some rungs on the way to photchemical heaven" Preprint available for download at
[url]http://dcm.ujf-grenoble.fr/PERSONNEL/CT/casida/research/SanDiego.pdf[/url]
[BAHK98] R. Bauernschmitt, R. Ahlrichs, F.H. Hennrich, and M.M. Kappes, J. Am. Chem. Soc. 120, 5052 (1998). Experiment versus Time Dependent Density Functional Theory Prediction of Fullerene Electronic Absorption
[C95] M.E. Casida, in Recent Advances in Density Functional Methods, Part I, edited by D.P. Chong (Singapore, World Scientific, 1995), p. 155. "Time-dependent density-functional response theory for molecules'' Preprint available for download at
[url]http://dcm.ujf-grenoble.fr/PERSONNEL/CT/casida/research/chong.ps[/url]
[deMon2k] The deMon2k program is described at the website
[url]http://www.demon-software.com/public_html/index.html[/url]
POSITION 2 : Improvement of TDDFT modeling of the spectroscopy of
nanosystems through better understanding of the space-time trade-off
in the exchange-correlation functional
Project Description :
The understanding of electronic excited states of nanometer size systems
is essential for the efficient development of molecular switches,
photobiology, and organic photovoltaic cells, to name just a few
examples. The currently most popular methodes for studying electronic
excited states are the Bethe-Salpeter equation (BSE) and time-dependent
density-functional theory (TDDFT [MUN+06]) in solid-state physics and
CASPT2 and TDDDFT in quantum chemistry. Of these methods, the linear
response formulation of TDDFT (sometimes called Casida's equations [C95])
is nominally the simplest and has become the single-determinant method of
chose for modeling the excited states of large and cocmplex systems.
Nevertheless certain problems remain [C01], in particular two notorious
problems which complicate the application of TDDFT to some particularly
important problems: underestimation of charge transfer excitations whose
understanding is often important in photobiologie, photochemistry, and
photovoltaics, annd the lack of an explicit description of excitations
of more than one electron, whose understanding is essential for describing
funnel regions in photochemical reactions. The origin of these problems
is in the approximate description of the TDDFT exchange-correlation
potential whose exact properties are relatively little known beyond the
adiabatic approximation. To clarify the nature of the needed corrections
to the xc functional it is proposed to use optimized effective potential
techniques [C95, HCS02] in the context of the BSE to find the pole
structure of the xc kernel in TDDFT [C05]. Given this structure, we will
create model xc kernels and we will implement them in efficient programs
for the above mentionned applications.
References :
[C95] M.E. Casida, in Recent Advances in Density Functional Methods, Part I, edited by D.P. Chong (Singapore, World Scientific, 1995), p. 155. "Time-dependent density-functional response theory for molecules''
[C99] M.E. Casida, Phys. Rev. B 59, 4694 (1999). "Correlated optimized effective potential treatment of the derivative discontinuity and of the highest occupied Kohn-Sham eigenvalue: A Janak-type theorem for the optimized effective potential method"
[C01] M.E. Casida, in Accurate Description of Low-Lying Molecular States and Potential Energy Surfaces, ACS Symposium Series 828, edited by Mark R. Hoffmann and Kenneth G. Dyall (ACS Press: Washington, D.C., 2002), ISBN 0-8412-3792-1, (Proceedings of ACS Symposium, San Diego, Calif., 2001), pp. 199-220. "Jacob's ladder for time-dependent density-functional theory: Some rungs on the way to photchemical heaven"
[HCS02] S. Hamel, M.E. Casida, and D.R. Salahub, J. Chem. Phys. 116, 8276 (2002). "Exchange-only optimized effective potential for molecules from resolution-of-the-identity techniques: Comparison with the local density approximation, with and without asymptotic correction"
[C05] Mark E. Casida, J. Chem. Phys. 122, 054111 (2005). "Propagator Corrections to Adiabatic Time-Dependent Density-Functional Theory Linear Response Theory"
[MUN+06] Time-Dependent Density-Functional Theory, edited by M.A.L. Marques, C. Ullrich, F. Nogueira, A. Rubio, and E.K.U. Gross, Lecture Notes in Physics (Springer: Berlin, 2006)
Prerequisites :
A Masters in Theoretical Chemistry and/or Physics is desirable as is a
knowledge of programming, but the most essential thing is an interest in
the methods of quantum chemistry and physics. We will use correlated
electronic structure methods at the fronteer between quantum chemistry
and solid-state physics: density-functional theory (DFT), time-dependent
DFT (TDDFT), many-body theory, and CASSCF. We will be lead to modify
quantum chemistry, and notably, DFT programs to test our ideas. The
student will be part of national (GdR-DFT++) and European (ETSF)
networks of theoreticians working on problems similar to those described
above.
POSITION 1 : Co-directed by Thierry Deutsch and Mark E. Casida
Potential candidates are requested to send a letter of application,
curriculum vitae, and recommendation letters to both
1)
Mark E. Casida
Professeur
Laboratoire de Chimie Thorique
Dpartement de Chimie Molcularie (DCM, UMR CNRS/UJF 5250)
Institut de Chimie Molculaire de Grenoble (ICMG, FR2607)
Universit Joseph Fourier (Grenoble I)
F38041 Grenoble
FRANCE
Tel: +33.4.76.63.56.28
e-mail: mark.casida^ujf-grenoble.fr
[url]http://dcm.ujf-grenoble.fr/PERSONNEL/CT/casida/[/url]
Secretary: Sylvie POCHOLLE
Tel: +33.4.76.63.57.06
Fax: +33.4.76.51.42.67
2) Thierry DEUTSCH
Laboratoire de simulation atomique
Dpartement de Recherche Fondamentale sur la Matire condense (DRFMC/SP2M/L_Sim)
CEA-Grenoble
Tel: +33.4.38.78.34.06
e-mail: Thierry.Deutsch^cea.fr
Electronic applications are encouraged. An acknowledgement will be
sent upon receipt.
POSITION 2 : Directed by Mark E. Casida
Potential candidates are requested to send a letter of application,
curriculum vitae, and recommendation letters to
Mark E. Casida
Professeur
Laboratoire de Chimie Thorique
Dpartement de Chimie Molcularie (DCM, UMR CNRS/UJF 5250)
Institut de Chimie Molculaire de Grenoble (ICMG, FR2607)
Universit Joseph Fourier (Grenoble I)
F38041 Grenoble
FRANCE
Tel: +33.4.76.63.56.28
e-mail: mark.casida^ujf-grenoble.fr
[url]http://dcm.ujf-grenoble.fr/PERSONNEL/CT/casida/[/url]
Secretary: Sylvie POCHOLLE
Tel: +33.4.76.63.57.06
Fax: +33.4.76.51.42.67
Electronic applications are encouraged.
An acknowledgement will be sent upon receipt.
[url]http://ccl.net/cca/jobs/joblist/mess0012817.shtml[/url] thanks 谢谢了
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