Ground state properties, transition metal

We presented selected results from a new tight-binding total energy method that accurately predicts ground state properties of transition and noble metals, and successfully extended to transition metal carbides. 

The first part of the chapter is devoted to an analysis of these correlations, as well as to the presentation of the most important experimental results. In a second part the following stage of development is reviewed, i.e. the introduction of more quantitative theories mostly based on bond structure calculations. These theories are given a thermodynamic form (equation of states at zero temperature), and explain the typical behaviour of such ground state properties as cohesive energies, atomic volumes, and bulk moduli across the series. They employ in their simplest form the Friedel model extended from the d- to the 5f-itinerant state. The Mott transition (between plutonium and americium metals) finds a good justification within this frame. 

The trends in several ground state properties of transition metals have been shown in Figs. 2, 3 and 15 of Chap. A and Fig. 7 of Chap. C. The parabolic trend in the atomic volume for the 3-6 periods of the periodic table plus the actinides is shown in Fig. 3 of Chap. A. We note that the trend for the actinides is regular only as far as plutonium and that it is also broken by several 3 d metals, all of which are magnetic. Similar anomalies for the actinides would probably be found in Fig. 15 of Chap. A - the bulk modulus - and Fig. 7 of Chap. C - the cohesive energy if more measurements had been made for the heavy actinides. 

The three basic ground state properties of the heavy actinides are more likely to follow those of the rare earths (Fig. 2 of Chap. A). The atomic volumes of the rare earth metals decrease monotonically with atomic number. This suggests, as will be explained more fully below, that the 4f electrons make little or no contribution to cohesion. They are said to be on the low density side of a Mott transition - with the notable exception of one of the phases of cerium. This is believed to be also the case for the second half of the actinide series ... 

Interpretation of X-ray absorption spectra (and most other types of coreelectron spectra) is complicated by the creation of a core hole in one of the atoms in the solid. In many cases (e.g., for transition and rare-earth metals) the magnitude of this effect is not known as yet. Further, these spectra depend on the excited states of the electronic system, which are less well understood than the corresponding ground-state properties (202). 

A comparison of analogous compounds shows no evidence that the observed dependence of the rate on the metal center arises from ground-state properties. Thus, a primary factor in the metal center reactivity is the transition state. This is similar to the conclusions regarding substitutional reactivity of classical coordination complexes, suggesting that similar interpretations may be possible. 

The LCGTO-Xa approach described so far has been successfully applied to a large variety of systems, including main group molecules (50,52,53), transition metal compounds, e.g. carbonyl complexes (27,28,55,56) and ferrocene (57), and a number of transition metal dimers (47). Besides these investigations on ground state properties useful information has also been obtained for selected problems involving excited states (52), such as the photolysis of Ni(CO)4 (58,59) and localized excitons in alkali halides (60) and in other ionic crystals ( ). 

GROUND STATE PROPERTIES OF TRANSITION METAL OXIDES... 

Later developments of linear methods have been in the direction of self-consistent calculations of ground-state properties utilising local spin-density-functional formalism [1.51,52] for exchange and correlation. The basis of the self-consistency procedure was given in papers by Madsen et al. [1.53], Vouisen et al. [1.54] and Andersen and Jepsen [1.55], and was soon followed by results for the magnetic transition metals [1.56], the noble metals [1.57], some lanthanides [1.58], the actinides [1.59,60], and the 3d transition metal monoxides [1.61,62]. In this context one should also mention calculations of the electronic structure in transition metal compounds [1.63,64], A15 compounds [1.65,66], rare-earth borides [1.67], Chevrel... 

H.L. Skriver, O.K. Andersen "Self-Consistent Calculations of Ground-State Properties for Ordered Transition Metal Alloys", in Transition Metals 1977, ed. by M.J.G. Lee, J.M. Perz, E. Fawcett, Institute of Physics Conf. Ser. No.39, 100 (1978)... 

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