Aula Magna (Dip. Matematica)

Optimal distribution of oppositely charged phases: Screening, charge neutrality and regularity

Tipo Seminario: 
Relatore: 
Hans Knupfer
We study the minimum energy configuration of a uniform distribution of negative charge subject to Coulomb repulsive self-interaction and attractive interaction with a fixed positively charged domain.
After having established existence and uniqueness of a minimizing configuration, we prove charge neutrality and the complete screening of the Coulomb potential exerted by the positive charge, and we discuss the regularity properties of the solution.
Data Seminario: 
Friday, February 12, 2016
Aula: 
Aula Magna (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 10:00
Affiliazione: 
Heidelberg Universitat
Ora Inizio: 
Saturday, January 1, 0000 - 09:00

Periodic striped ground states in Ising models with competing interactions

Tipo Seminario: 
Relatore: 
Alessandro Giuliani

We consider Ising models in two and three dimensions, with short range ferromagnetic and long range, power-law decaying, antiferromagnetic interactions. We let J be the ratio between the strength of the ferromagnetic to antiferromagnetic interactions. The competition between these two kinds of interactions induces the system to form domains of minus spins in a background of plus spins, or vice versa.

Data Seminario: 
Thursday, February 11, 2016
Aula: 
Aula Magna (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 11:30
Affiliazione: 
Universita' di Roma Tre
Ora Inizio: 
Saturday, January 1, 0000 - 10:30

Carbon geometries as minimizers

Tipo Seminario: 
Relatore: 
Ulisse Stefanelli

Carbon nanostructures are identified with configurations of atoms interacting via empirical potentials.
The specific geometry of covalent bonding in carbon is phenomenologically described by the combination of an attractive-repulsive two-body interaction and a three-body bond-orientation part.
We investigate the strict local and global minimality of specific carbon configurations under general assumptions on the interaction potentials. In particular, we discuss the stability of carbyne, graphene, some fullerenes, and diamond.

Data Seminario: 
Thursday, February 11, 2016
Aula: 
Aula Magna (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 10:00
Affiliazione: 
Wien Universitat
Ora Inizio: 
Saturday, January 1, 0000 - 09:00

Crystallization Results for Optimal Location Problems

Tipo Seminario: 
Relatore: 
David Bourne

While it is believed that many particle systems have periodic ground states, there are few rigorous crystallization results in two and more dimensions.
In this talk I will show how results by the Hungarian geometer László Fejes Tóth can be used to prove that an idealised block copolymer energy is minimised by the triangular lattice. I will also discuss a numerical method for a broader class of optimal location problems and some conjectures about minimisers in three dimensions.
This is joint work with Mark Peletier, Steven Roper and Florian Theil. 

Data Seminario: 
Wednesday, February 10, 2016
Aula: 
Aula Magna (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 17:00
Affiliazione: 
Durham University
Ora Inizio: 
Saturday, January 1, 0000 - 16:00

Variational analysis of material defects and crystal plasticity

Tipo Seminario: 
Relatore: 
Adriana Garroni
Dislocations are line defects in the crystalline structure of metals. They are considered the main mechanism for plastic deformation and their interaction at the microscopic scale are relevant to understand complex phenomena as yielding and hardening.
Data Seminario: 
Wednesday, February 10, 2016
Aula: 
Aula Magna (Dip. Matematica)
Ora Fine: 
Saturday, January 1, 0000 - 15:30
Affiliazione: 
Universita' di Roma La Sapienza
Ora Inizio: 
Saturday, January 1, 0000 - 14:30

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