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BEGIN:VEVENT
DTSTAMP:20260824T125041Z
LAST-MODIFIED:20201002T170010Z
DTSTART:20201016T150000Z
DTEND:20201016T160000Z
UID:event2360@bu.edu
URL:http://physics.bu.edu/internal/events/show/2360
SUMMARY:Catastrophe theory classification of Fermi surface topological tran
	sitions in two dimensions
DESCRIPTION:Featuring Anirudh Chandrasekaran\, Boston University\, Physics 
	Department\n\nPart of the Preliminary Oral Exam.\n\nWe classify singulariti
	es in the electronic dispersion of two-dimensional systems that occur when 
	the Fermi surface changes topology\, using catastrophe theory. For systems 
	with up to seven control parameters (i.e.\, pressure\, strain\, bias voltag
	e\, etc)\, the theory guarantees that the singularity belongs to one of sev
	enteen standard types known as catastrophes. We show that at each of these 
	singularities the density of states diverges as a power law\, with a univer
	sal exponent characteristic of the particular catastrophe\, and we provide 
	its universal ratio of amplitudes of the prefactors for energies above and 
	below the singularity. We further show that crystal symmetry restricts whic
	h types of catastrophes can occur at the points of high symmetry in the Bri
	llouin zone. For each of the seventeen wallpaper groups in two-dimensions\,
	 we list which catastrophes are possible at each high symmetry point.\n\n--
	-\n\nJoin Zoom Meeting\nhttps://bostonu.zoom.us/j/95912240458?pwd=bjVBaGc0d
	HNRQUZrb2hodDJGNGJMQT09\n\nMeeting ID: 959 1224 0458\nPasscode: 542867
LOCATION: \, \, 
STATUS:CONFIRMED
CLASS:PUBLIC
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