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SUMMARY:The challenge to deliver high accuracy for material science on lar
 ge computer simulations - Andrea Zen
DTSTART:20210303T113000Z
DTEND:20210303T123000Z
UID:TALK156010@talks.cam.ac.uk
CONTACT:Chuck Witt
DESCRIPTION:Computer simulations are becoming useful in providing insight 
 in the physical and chemical processes taking places in nature. Simulation
 s yield molecular level understanding\, which is often complementary infor
 mation to the understanding provided by experimental investigations. Yet\,
  they are only useful when when they can accurately model the physical sys
 tem. High accuracy is often only obtained by resorting to first principles
 \, and by modelling the quantum mechanics features of the system of intere
 st at the atomic level.\nThriving nanotechnologies and exciting experiment
 s pose big challenges to computational approaches. On the one hand\, the s
 ystems to be simulated are large and computationally expensive\, and their
  physical and thermal properties require sampling of a large phase space (
 using molecular dynamics or other techniques). On the other hand\, the hig
 h accuracy required to evaluate inter-atomic interactions often means usin
 g very accurate and expensive approaches to solve the Schrodinger equation
 . We discuss here some of the most accurate approaches available to assess
  the ground state electronic states and their properties in molecular syst
 ems\, solids and surfaces\, namely quantum Monte Carlo (QMC) methods. QMC 
 simulations are computationally expensive and often demands the employment
  of high performance computers. \nHowever\, recent developments have drast
 ically reduced the overall cost of QMC\, especially in the evaluation of i
 nteraction energies. QMC methods can be used to benchmark cheaper but less
  accurate approaches (such as density functional theory\, or empirical for
 ce fields) promoting their further developments. The combination of this h
 ierarchy of methods\, coupled with machine learning techniques\, then prov
 ides high accuracy for systems whose size would preclude a full quantum me
 chanics approach.
LOCATION:Zoom
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