Crystal field theory thermodynamic stability

Perhaps a more fundamental application of crystal field spectral measurements, and the one that heralded the re-discovery of crystal field theory by Orgel in 1952, is the evaluation of thermodynamic data for transition metal ions in minerals. Energy separations between the 3d orbital energy levels may be deduced from the positions of crystal field bands in an optical spectrum, malting it potentially possible to estimate relative crystal field stabilization energies (CFSE s) of the cations in each coordination site of a mineral structure. These data, once obtained, form the basis for discussions of thermodynamic properties of minerals and interpretations of transition metal geochemistry described in later chapters. 

One of the most successful applications of crystal field theory to transition metal chemistry, and the one that heralded the re-discovery of the theory by Orgel in 1952, has been the rationalization of observed thermodynamic properties of transition metal ions. Examples include explanations of trends in heats of hydration and lattice energies of transition metal compounds. These and other thermodynamic properties which are influenced by crystal field stabilization energies, including ideal solid-solution behaviour and distribution coefficients of transition metals between coexisting phases, are described in this chapter. 

Among the early successes of crystal field theory was its ability to account for magnetic and spectral properties of complexes. In addition, it provided a basis for understanding and predicting a number of their structural and thermodynamic properties. Several such properties are described in this section from the crystal field point of view. Certainly other bonding models, such as molecular orbital theory, can also be used to interpret these observations. Even when they are, however, concepts from crystal field theory, such as crystal (or ligand) field stabilization energy, are often invoked within the discussion. 

The history of gas hydrate research, its physical and thermodynamics properties, and the impact on energy and the environment have been presented in several excellent books and reviews.This chapter is focused on the molecular aspect, particularly, on the application of different computational methods to investigate structural and thermodynamic stability, guest and lattice dynamics, thermal transport and mechanisms for homogeneous and heterogeneous crystallization. Even within this restricted choice of topics, there are numerous contributions to the modelling of hydrate properties. This chapter is not intended to provide a comprehensive review on the field of computational gas hydrate research. Even within the topics chosen no attempt was made to exhaustively review available literatures and competing theories. Rather, the... 

---