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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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Embedding approaches for large complex systems, including the extended ONIOM method XO and the DCMB method

Xin Xu
Fudan University, China, China

Abstract

Calculation of large complex systems remains to be a great challenge, where there is always a trade-off between accuracy and efficiency. We have proposed the eXtended ONIOM method (XO) which surmounts some inherited limitations of the popular ONIOM method by introducing the Inclusion Exclusion Principle used in the fragmentation methods. We have also proposed the DCMB method, which is a combination of a parallel divide-and-conquer (DC) method and a mixed-basis (MB) set scheme.

In this talk, I will discuss some general guidelines for the construction of a good XO scheme. In particular, force-error test is proposed to quantitatively validate the usefulness of an XO scheme, taking accuracy, efficiency and scalability all into account. Representative studies on zeolites, polypeptides and cyclodextrins have been carried out to demonstrate how to strive for high accuracy without sacrificing efficiency. As a natural extension, XO has been applied to calculate the total energy, fully optimized geometry and vibrational spectra of the whole system, where ONIOM becomes inapplicable.

In the DCMB approach, atomic forces, total energy and vibrational frequencies are obtained from a series of MB calculations, which are derived from the target system utilizing the DC concept. Unlike the fragmentation based methods, all DCMB calculations are performed over the whole target system and no artificial caps are introduced so that it is particularly useful for charged and/or delocalized systems.

Applications to accurate prediction of the protein-ligand binding energies and structures, computational study of anion-π interactions, a mechanistic viewpoint for formation of acrylates from ethylene and CO2 on Ni complexes, etc. will be discussed.



References


1. Wenping Guo, Anan Wu, Xin Xu, Chem. Phys. Letters, 498 (2010) 203-208.
2. Zhengkun Chu, Gang Fu, Wenping Guo, Xin Xu, J. Phys. Chem. C 115(30) (2011) 14754-14761.
3. Anan Wu, Xin Xu, J. Comput. Chem. 33 (2012) 1421-1432.
4. Wenping Guo, Anan Wu, Igor Ying Zhang, Xin Xu, J. Comput. Chem. 33 (2012) 2142-2160.
5. Li Rao, Igor Ying Zhang, Wenping Guo, Eric Meggers, Xin Xu, J. Comput. Chem., 34(2013)1636-1646.
6. Wenping Guo, Carine Michel, Renate Schwiedernoch, Raphael Wischert, Xin Xu, Philippe Sautet, Organometallics, 33 (2014) 6369–6380.
7. Jinynag Xi, and Xin Xu, Phys. Chem. Chem. Phys., 18 (2016) 6913-6924.
8. Li Rao, Bo Chi, Yanliang Ren, Yongjian Li, Xin Xu, Jian Wan, J. Comput. Chem., 37 (2016) 336-344.