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In this chapter, the author concentrates on the anion work, which has identified 114 bound states in the lanthanides and 41 bound states in the actinides, over half of which are new predictions. In two anions, Ce‐ and La‐, bound opposite parity states were found, making a total of 3 [Os‐]. Bound‐to‐bound transitions have been observed in Ce‐ and may have been observed in La‐. The chapter discusses...
This chapter addresses high‐accuracy calculations of actinide systems. Lanthanide systems, where the broader availability of experimental data provides more extensive checks of computed properties, are discussed. The chapter presents predictions for the eka‐actinide atoms E121 (eka‐Ac) and E122 (eka‐Th). Actinides (as well as their lanthanide homologues) present severe problems to theory and computations,...
This chapter provides a critical review of the use of 2‐ and 4‐component relativistic Hamiltonians combined with all‐electron methods and appropriate basis sets for the study of lanthanide and actinide chemistry. These approaches provide in principle the more rigorous treatment of the electronic structure but typically demand large computational resources due to the large basis sets that are required...
Lanthanide compounds generally have significant photoluminescent and magnetic properties, which arise from the characteristics of the localized 4f open‐shell electrons. This chapter discusses the electronic structure of diatomics containing lanthanide atoms. It also discusses the method used in the calculations. The chapter gives the Mulliken gross atomic populations (GAOP) of the respective molecular...
The electronic structure associated with elements present in the f‐block of the periodic table, namely the lanthanides (Ln) and actinides (An), is both highly interesting and highly complex. This chapter considers the quantum chemical simulation of actinide and lanthanide complexes. It discusses the need for a multiconfigurational description of the wavefunction, and introduces the complete‐active‐space...
The idea of effective core potentials (ECPs) is based on the chemically intuitive restriction of the explicit calculations to the chemical important valence electrons, while the essentially inert atomic cores, i.e., the nucleus and the electrons in the inner shells, are replaced by a suitable parametrized (relatively simple) one‐electron operator acting on the remaining valence electrons, i.e., the...
Application of quantum chemical methods to molecules of chemical interest requires expansion of (one‐particle) wavefunctions by basis functions. For many computer programs in quantum chemistry, it is economically advantageous to use so‐called segmented contracted sets, for which atomic shells are not fitted as a whole, but by segments. This scheme, which allows but also requires certain flexibility...
Molecules containing f‐block elements, particularly the actinides, are currently of very strong interest due to their role in the nuclear fuel cycle and waste remediation efforts. Fundamental studies on small molecular systems involving f‐block elements have been an active area for both experiment and theory, since the results and insights arising from these studies can often be used for understanding...
Lanthanide‐activated solid‐state lasers, scintillators, and lamps reflect the ability of the lanthanide ions to absorb, transfer, exchange, and emit light under the influence of the host crystal, which deforms and multiplies the lanthanide's atomic electronic states in various ways and extents, until local electronic states arise in the imperfect crystal, which are rooted in the lanthanide and capable...
The year 2012 marked the golden anniversary of the Judd‐Ofelt (J‐O) theory as a tool used widely for the theoretical description of the spectroscopic properties of the lanthanide materials; in fact it is the only tool, as pointed out in the title of this chapter, that is used in ab initio type calculations. The chapter discusses the advantages and limitations of the Judd‐Ofelt theory when applied...
The theoretical modeling of lanthanide and actinide complexes in condensed media is challenging for theoretical chemistry, due in part to the intrinsic general challenge of devising a reliable model of the species in such environments and the necessity of ‘chemical’ accuracy. This chapter discusses the requirements, challenges, and pitfalls associated with attempting to theoretically model molecular...
This chapter focuses on methodological and computational aspects that are key to accurately modeling the spectroscopic and thermodynamic properties of molecular systems containing actinides within the density functional theory (DFT) framework. It discusses two methods that account for relativistic effects, the zeroth‐order regular approximation (ZORA) and the eXact 2‐Component (X2C) Hamiltonian. The...
From an experimental point of view, there have been impressive improvements on the synthesis procedure and more importantly on the chemical stabilization of the synthesized complexes. Density functional theory (DFT) in particular is an important tool for the prediction of electronic structures, plausible mechanisms, and spectroscopic data involving complexes of d‐transition, lanthanide, and actinide...
This chapter focuses on computational studies that relate directly to the fundamental issue in chemistry: making and breaking chemical bonds. It emphasizes that this contribution is not meant to be a review of such studies in f‐element complexes. The chapter explains the definition of some terms and a discussion of some of the issues associated with relativity and how they are typically treated within...
The Lewis octets and the 18‐electron principle are well‐known, and are thought to correspond to filling the (s, p)‐like and (s, p, d)‐like shells, respectively, for an MLn complex. The chapter describes the work of Cui et al, where a new class of Zintl ions, plumbaspherene, Pb2‐12, and stannaspherene, Sn2‐12, were characterized by photoelectron spectroscopy as hosts for building up a new type of endohedral...
This chapter describes some important aspects of the shell structure, relativistic effects, and electron correlation effects for lanthanide and actinide atoms and molecules, mainly using the example of Cerium (Ce) and Thorium (Th). It turns to a discussion of the electronic structure of cerium‐bis(η8‐cyclooctatetraene), cerocene, which fascinated this author for more than two decades, as well as a...
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