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PhD házivédésMáté MihályHUN-REN Wigner FK SZFIStudying strongly correlated 
systems with tensor network state methods and quantum information theory2024. 
január 25. csütörtök, 10.00, KFKI Telephely, I. épület 1. emeleti 
TanácsteremAlthough the density matrix renormalization group (DMRG) method 
was developed to simulate one-dimensional strongly correlated systems in 
solid-state physics, it also shows its potential in higher-dimensional as 
well as in many other strongly correlated many-body problems. In my thesis, I 
investigate the application of DMRG in quantum chemistry and in ultracold 
physics.First, the coupled cluster method tailored by DMRG was investigated 
theoretically and exemplified numerically by the nitrogen dimer for different 
geometries. The analysis showed the robustness of entropic quantities and 
provide a protocol for optimal basis splitting [1]. Second, orbital 
optimization based on entanglement minimization within the framework of 
two-site DMRG was studied and numerically exemplified, which showed that the 
multireference character of the wave function can be compressed [2]. Third, 
the Hubbard wheel model of hard-core bosons was proposed and investigated 
theoretically and numerically. The tuning of just a single control parameter 
allows a crossover from one- to “infinite”-dimensionality, which also drives 
a transition from quasi-condensation to complete Bose--Einstein condensation 
[3].[1] Faulstich, Máté, Laestadius, Csirik, Veis, Antalik, Brabec, 
Schneider, Pittner, Kvaal, Legeza. J. Chem. Theory Comput., 15, 4, 2206 
(2019) [2] Máté, Petrov, Szalay, Legeza. J. Math. Chem., 61 (2), 362, (2023) 
[3] Máté, Legeza,  Schilling, Yousif, Schilling. Commun Phys 4, 29 
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