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SUMMARY:How Good is Damped Molecular Dynamics as a Method for Simulating R
 adiation Damage in Metals? - Matthew Foulkes (Imperial College London)
DTSTART:20090302T160000Z
DTEND:20090302T170000Z
UID:TALK15564@talks.cam.ac.uk
CONTACT:Ian Farnan
DESCRIPTION:Classical molecular dynamics (MD) is often used to study radia
 tion\ndamage cascades because it provides information on time and length\n
 scales inaccessible to experiment. In a radiation damage process\, energy\
 ntransfer from ions to electrons may be important\, but there is continued
 \nuncertainty over how to incorporate such effects in MD. We use quantum\n
 mechanical simulations to evaluate different approaches. The\nirreversible
  transfer of energy from fast ions to electrons does not\ntake place in co
 nventional Born-Oppenheimer quantum MD simulations\, but\ncan be studied u
 sing Ehrenfest-based quantum MD. Our Ehrenfest\nsimulations suggest that a
  damping force proportional to velocity is\nsufficient to model energy tra
 nsfer from ions to electrons in most low\nenergy cascades. We also find\,
  however\, that a larger rate of energy\ntransfer is seen when the ionic k
 inetic energy is confined to a focused\nsequence of collisions. A viscous
  damping coefficient dependent on the\nlocal atomic environment is shown t
 o be an excellent model for\nelectronic energy losses in low energy cascad
 es in metals.\n\nBibliography\n\n"Electronic Excitations and their Effect 
 on the Interionic Forces in\nSimulations of Radiation Damage in Metals"\,\
 nC.P. Race\, D.R. Mason and A.P. Sutton\,\nJ. Phys.: Condens. Matter 21\, 
 115702 (2009)\n\n"How Good is Damped Molecular Dynamics as a Method to Sim
 ulate \nRadiation Damage in Metals?"\nJ. le Page\, D.R. Mason\, C.P. Race\
 , and W.M.C. Foulkes\nNew J. Phys. {\\bf 11}\, 013004-1 (2009)\n\n"The Ehr
 enfest Approximation for Electrons Coupled to a Phonon System"\nJ. le Page
 \, D.R. Mason and W.M.C. Foulkes\nJ. Phys.: Condens.~Matter 20\, 125212-1 
 (2008)\n\n"Electronic Damping of Atomic Dynamics in Irradiation Damage of 
 Metals"\nD.R. Mason\, J. le Page\, C.P. Race\, W.M.C. Foulkes\, M.W. Finni
 s\, \nand A.P. Sutton\nJ. Phys.: Condens. Matter 19\, 436209-1 (2007)
LOCATION:Harker 2 lecture room\, Department of Earth Sciences\, Downing Si
 te
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