New Theoretical Models for High Precision Coupled Cluster Calculations

Event Sponsor: 
Computing, Environment and Life Sciences
Start Date: 
Apr 7 2010 - 10:30am to 11:30am
Building 240 Room 4301
Argonne National Laboratory
Dr. Karol Kowalski
Speaker(s) Title: 
Senior Research Scientist IV William R. Wiley Environmental Molecular Sciences Laboratory Pacific
Dr. Raymond Bair

Over the last few decades coupled cluster (CC) theory has evolved into a basic formalism and has been used to describe a gamut of many-electron systems.
This can be attributed to three major factors:
(1) the development of new CC methods capable of providing highly-accurate description of correlation effects in
three basic domains of CC theory: ground- and excited-state methods and linear response theory
(2) the development of highly scalable CC codes capable of
being executed across large numbers of CPUs
(3) the development of multiscale CC-based approaches such as QM/MM methods or Embedded Cluster approaches where the CC method plays an essential role in describing the so-called quantum region (which is described by the first-principle approaches in the multiscale framework).

These combined approaches have led to the emergence of new application domains for CC methods including the
calculations for electronic structure of biologically relevant systems and excited-state calculations for surface localized states. Since the highly-accurate CC formalisms will define a next generation of quantum chemistry imulations,in this talk we will discuss two newly developed formalisms - ground-state coupled-cluster methods based on the use of generating functional and non-iterative Equation-of-Motion CC methods, which significantly improve the balance between the ground- and excited-state correlation effects.

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