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Workshops

Quantum-chemistry methods for materials science

November 8, 2017 to November 10, 2017
Location : CECAM-HQ-EPFL, Lausanne, Switzerland
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Wave-funtion-based methodology as a route to controllable accuracy in solid state applications

Denis Usvyat
Institute for Physical and Theoretical Chemistry, Regensburg University, Germany

Abstract

The wave-function-based approach to the electronic structure problem offers a hierarchy of approximate models that converge to the exact treatment. This rich methodological hierarchy allows one to systematically estimate or even eliminate errors originating from the underlying approximations and also provides a tool to treat difficult multireference cases. For solids, however, the wave-function-based techniques are computationally very demanding. We address this problem by applying the local correlation framework combined with different embedding schemes. This includes the local periodic LMP2 [1,2], mean-field-embedded local coupled cluster [2,3] and CASCI [4] methods. The first two approaches can be combined in a form of an accurate computational protocol for weakly correlated periodic systems [3,5], while the latter, which is processed via the FCI-QMC treatment [6], can be applied to study local multireference defects in solids.



References

[1] D. Usvyat, L. Maschio and M. Schütz, J. Chem. Phys., 143, 102805 (2015)
[2] O. Masur, M. Schütz, L. Maschio and D. Usvyat, J. Chem. Theory Comput. 12, 5145 (2016)
[3] M. Schütz, L. Maschio, A. J. Karttunen and D. Usvyat, J. Phys. Chem. Lett. 8, 1290 (2017)
[4] D. Usvyat and A. Alavi, in preparation
[5] D. Usvyat, J. Chem. Phys. 143, 104704 (2015)
[6] N. S. Blunt, S. D. Smart, J. A. F. Kersten, J. S. Spencer, G. H. Booth and A. Alavi, J. Chem. Phys 142, 184107 (2015)