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SUMMARY:The challenge to deliver high accuracy for material science on lar
 ge computer simulations - Andrea Zen\, UCL
DTSTART:20210121T140000Z
DTEND:20210121T150000Z
UID:TALK155005@talks.cam.ac.uk
CONTACT:Jan Behrends
DESCRIPTION:Computer simulations are becoming useful in providing insight 
 in the physical and chemical processes taking places in nature. \nSimulati
 ons yield molecular level understanding\, which is often complementary inf
 ormation to the understanding provided by experimental investigations. \nY
 et\, they are only useful when when they can accurately model the physical
  system.\nHigh accuracy is often only obtained by resorting to first princ
 iples\, and by modelling the quantum mechanics features of the system of i
 nterest at the atomic level.\nThriving nanotechnologies and exciting exper
 iments pose big challenges to computational approaches. On the one hand\, 
 the systems to be simulated are large and computationally expensive\, and 
 their physical and thermal properties require sampling of a large phase sp
 ace (using molecular dynamics or other techniques). \nOn the other hand\, 
 the high accuracy required to evaluate inter-atomic interactions often mea
 ns using very accurate and expensive approaches to solve the Schrodinger e
 quation. \nWe discuss here some of the most accurate approaches available 
 to assess the ground state electronic states and their properties in molec
 ular systems\, solids and surfaces\, namely quantum Monte Carlo (QMC) meth
 ods. \nQMC simulations are computationally expensive and often demands the
  employment of high performance computers. \nHowever\, recent developments
  have drastically reduced the overall cost of QMC\, especially in the eval
 uation of interaction energies.\nQMC methods can be used to benchmark chea
 per but less accurate approaches (such as density functional theory\, or e
 mpirical force fields) promoting their further developments. The combinati
 on of this hierarchy of methods\, coupled with machine learning techniques
 \, then provides high accuracy for systems whose size would preclude a ful
 l quantum mechanics approach.
LOCATION:Details of video conferencing will be distributed nearer the time
 .
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