Oberseminar Stochastik: Prof. Dr. Evgenij Spodarev (Universität Ulm): Random Eigenvalues of Fullerenes, Graphene and Nanotubes
Wednesday, 12.11.2025 16:00 im Raum SRZ 216/217
Mathematical fullerenes are convex polyhedra with pentagonal and hexagonal faces only.
By Euler-Eberhard theorem, any fullerene with n vertices has exactly 12 pentagonal and
n/2?10 hexagonal facets. The number of combinatorially non-equivalent fullerenes (isomers)
with n vertices (playing the role of carbon atoms in chemistry) grows as O(n9), making
statistical approaches essential for understanding their properties.
This talk presents a study of spectral properties of fullerenes and related carbon nanos-
tructures (graphene and nanotubes). We introduce random eigenvalues ?(Tn) of dual fullerene
graphs obtained by choosing an eigenvalue uniformly from the spectrum of its adjacency
matrix. We derive explicit (asymptotic as n ? ?) probability distribution functions and
moment generating functions for these random eigenvalues, revealing intricate dependence
on the combinatorial structure of the hexagonal planar lattice (graphene).
For carbon nanotubes, classified by their chiral indices (p, q) into armchair (p = q), zigzag
(q = 0), and chiral (p > q > 0) types, we establish exact formulas for the probability density
functions of random eigenvalues in the infinite nanotube limit. The analysis distinguishes
between metallic and semiconducting nanotubes based on the divisibility condition of p ? q
by 3. We prove weak convergence of random eigenvalues of infinite (p, q)-nanotubes to the
limiting distribution of random eigenvalues of infinite graphene as p + q ? ?.
Finally, if time permits, we present some open problems. The results combine methods
from spectral graph theory, probability theory, and combinatorics, offering new perspectives
on the mathematical structure of carbon nanomaterials.
Angelegt am 27.10.2025 von Claudia Giesbert
Geändert am 11.11.2025 von Claudia Giesbert
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