Microscopic description of collective excitations in deformed atomic nuclei

disertacija

• Naslov (hrvatski): Mikroskopski opis kolektivnih pobuđenja u deformiranim atomskim jezgrama
• Autor: Antonio Bjelčić
• Mentor: Tamara Nikšić (mentor)
• Član povjerenstva: Nils Paar (predsjednik povjerenstva)
• Član povjerenstva: Tamara Nikšić (član povjerenstva)
• Član povjerenstva: Igor Gašparić (član povjerenstva)
• Ustanova koja je dodijelila akademski / stručni stupanj: Sveučilište u Zagrebu; Prirodoslovno-matematički fakultet; (Fizički odsjek); Zagreb
• Datum i država obrane: 2022-12-19, Hrvatska
• Znanstveno / umjetničko područje, polje i grana: PRIRODNE ZNANOSTI; Fizika
• Univerzalna decimalna klasifikacija (UDC): 53 - Fizika

Sažetak

The Quasiparticle Random-Phase Approximation (QRPA) based on the nuclear energy density functionals (EDF) is one of the most widely used theoretical frameworks for describing collective excitations in deformed atomic nuclei. Since the configurational space of quasiparticle excitations can become very large, especially for heavy deformed nuclei, the standard matrix eigendecomposition solution of the QRPA equation is often prohibitive in terms of computational resources. Recently, the Finite Amplitude Method (FAM) with its quasiparticle adaptation (QFAM) has been proposed as a feasible method for solving the QRPA equation. Within this doctoral research, a highly efficient implementation of the QFAM solver based on the relativistic nuclear energy density functionals has been developed, namely the DIRQFAM solver in a form of a program package. Due to its efficiency, the developed DIRQFAM solver is suitable for describing collective excitations in axially symmetric atomic nuclei with quadrupole deformed ground states. Even heavy systems and systematic large-scale calculations are within reach. In this dissertation, the implementation of QFAM solver is presented and discussed, together with a new proposed method called the Kernel Polynomial Method (KPM). The KPM method is built on top of QFAM solver and uses QFAM iterations as a means to find the expansion coefficients of the QRPA response function which is expanded in terms of kernel-adjusted Chebyshev polynomials. It is shown that for non-relativistic EDF, the KPM method significantly outperforms the conventional QFAM approach in terms of computational complexity. Two applications of the developed QFAM solver are covered: i) exploration of low-energy response function on multipole excitations in light α-conjugate N = Z nuclei, and ii) description of quasiparticle-vibration coupling in deformed systems where QFAM is used to provide the phonon degrees of freedom for Dyson equation.

Sažetak (engleski)

Rad ne sadrži sažetak na drugom jeziku.

• Ključne riječi: energy density functional; relativistic mean-field theory; Hartree- Bogoliubov; relativistic Hartree-Bogoliubov; quasiparticle random phase approximation; finite amplitude method; nuclear cluster
• Ključne riječi (hrvatski): energijski funkctional gustoće; relativistička teorija srednjeg polja; Hartree-Bogoliubov; relativistički Hartree-Bogoliubov; kvazičestična aproksimacija slučajnih faza; metoda konačnih amplituda; vibracije
• Jezik: engleski
• URN:NBN: urn:nbn:hr:217:081955
• Datum promocije: 2023
• Studijski program: Naziv: Fizika; Vrsta studija: sveučilišni; Stupanj studija: poslijediplomski doktorski; Akademski / stručni naziv: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (dr. sc.)
• Vrsta resursa: Tekst
• Opseg: 155 str.
• Način izrade datoteke: Izvorno digitalna
• Prava pristupa: Otvoreni pristup
• Datum i vrijeme pohrane: 2023-07-13 08:54:04