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SUMMARY:Dynamical mean-field theory applied to linear scaling density func
 tional theory - Cedric Weber (TCM)
DTSTART:20120509T100000Z
DTEND:20120509T104000Z
UID:TALK37046@talks.cam.ac.uk
CONTACT:Dr. Mike Towler
DESCRIPTION:Phenomena that are connected to quantum mechanics\, such as ma
 gnetism\,\ntransport\, and the effect of impurity atoms and disorder\, and
  their relation to\nmaterial design and energy needs are important for alm
 ost every branch of the\nindustry. Density functional theory (DFT) was suc
 cessful at making accurate\npredictions for many materials\, in particular
  compounds which have a metallic\nbehaviour.  DFT combines high accuracy a
 nd moderate computational cost\, but the\ncomputational effort of performi
 ng calculations with conventional DFT\napproaches is still non negligible 
 and scales with the cube of the number of\natoms.  A recent optimised impl
 ementation of DFT was however shown to scale\nlinearly with the number of 
 atoms (ONETEP)\, and opened the route to large scale\nDFT calculations.\n\
 nNonetheless\, one bottleneck of DFT and ONETEP\, is that it fails at desc
 ribing\nwell some of the compounds where strong correlations are present\,
  in particular\nbecause the computational scheme has to capture both the b
 and-like character of\nthe uncorrelated part of the compound and the Mott-
 like features emerging from\nthe local strongly correlated centres.  A rec
 ent progress has been made in this\ndirection by the dynamical mean-field 
 theory (DMFT)\, that allows to describe\nthe two limits (metal and insulat
 or) in a remarkable precise way when combined\nwith DFT.\n\nThe ONETEP+DMF
 T implementation will be shortly discussed\, and its applications\nillustr
 ated by two examples:  i) the interplay of Mott and Anderson\nlocalization
  within disordered Vanadium dioxide and ii) a typical biological\nmolecula
 r system\, iron porphyrin\, which plays an important biological function\n
 in human haemoglobin.\n
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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