Computational studies of radionuclide uptake by mineral surfaces at the atomic scale

  • Angeliki Christodoulidou

Student thesis: Phd


The present thesis focuses on studying the adsorption of uranium and neptunium on important mineral surfaces at the atomic scale using computational methods. The hybrid density functional theory (DFT) employed within the periodic electrostatic embedded cluster method (PEECM) has been used to model the [010] goethite and [1014] calcite surfaces, and subsequently their interaction with charged and neutral U(VI) and Np(V) species. Chapters 1 introduces the purpose of the research project, the environmental relevance of the species under investigation and provides a critical review of the relevant literature, while Chapter 2 gives an overview of the background theory which is the basis of the computational methods applied in this study. In Chapter 3, the PEECM was initially used to study the electronic structure of goethite in order to create reliable surface models for the description of the adsorbent/adsorbate interactions. The calculated density of states of bulk goethite obtained using a hybrid functional correctly characterised the mineral as charge-transfer insulator. In Chapter 3, the PEECM is further used to explore isolated adsorption sites for uranium on goethite. In Chapters 4,5 and 6, the PEECM model in combination with quantum theory of atoms-in-molecules (QTAIM) analysis, natural localised molecular orbital (NLMO) analysis and simulated extended x-ray absorption fine-structure (EXAFS) spectra were used to gain insight into the adsorption interactions of U(VI) and Np(V) on the selected mineral surfaces. Both actinide elements were found to adsorb on the surfaces via inner-sphere monodentate and bidentate coordination, with the later mode found to produce less stable structures according to the calculated adsorption and reaction energies. Chapter 7 summarises the general conclusions deduced from the results produced throughout this thesis.
Date of Award1 Aug 2022
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorSamuel Shaw (Supervisor), Louise Natrajan (Supervisor) & Nikolas Kaltsoyannis (Supervisor)


  • Calcite
  • Geological Disposal
  • Nuclear Waste
  • NBO
  • Goethite
  • DFT
  • Uranium
  • Quantum Chemical calculations
  • Neptunium
  • Actinides
  • Adsorption

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