Metallic Electronic States Research Articles

Origin of delocalization in organic molecular conductors

The delocalization of electron states in one-dimensional metals, such as TTF-TCNQ, accounts for the observed itinerant motion of the electrons at temperatures above about 50 K. This delocalization is related to the extended nature of the molecules in organic metals, which causes the amplitude for forward scattering by the phonons to exceed the amplitude for backward scattering by an order of magnitude. The large forward scattering, which delocalizes the electrons, does not contribute to the resistivity in the delocalized state.

Liquid Metals: An Introduction to the Physics and Chemistry of Metals in the Liquid State

Mitsuo Shimoji London: Academic 1977 pp xv + 391 price £16.50 This is an important book for all interested in liquid metals, containing as it does a fairly complete account of developments up to about 1974–5. Perhaps the best way to indicate the flavour and approach is to give the chapter headings in order: thermal properties of liquid metals, thermal properties of liquid alloys, static structure of liquid metals and alloys, electron–ion interaction and cohesive energy of liquid metals, electron states in liquid metals and alloys, atomic transport properties, electron transport properties, transition to the nonmetallic states, heterogeneous equilibria and surface properties.

Electron states in liquid metals: especially optical and magnetic properties

The theory of optical absorption of the simple liquid metals (e.g. the alkalis) is outlined. At not too large frequencies, the Drude theory is regained. The relaxation time is that given by the weak scattering (Ziman) theory of electrical resistivity. For high frequencies, the relaxation time, however, becomes frequency dependent. Appreciable structure enters the theory, arising from collective excitations. The relation to recent ellipsometric measurements on liquid Na is briefly discussed. The optical conductivity and density of states in the divalent metals Hg and Be is then discussed, followed by the relation between photoemission and soft X-ray experiments and current electron theory. Specific attention is given to the evidence for a pseudo-gap in the divalent metals and to changes in the electron states which occur on melting the noble metals.The second major area treated is concerned with the magnetic properties of liquid metals. The theory of orbital and spin magnetism in simple liquid metals is reviewed and confronted with experiment. It is clear that the electron–electron enhancement effects have a dominant influence on the trend of the spin susceptibility of simple liquid metals as a function of density. However, electron–ion interactions must be introduced as corrections to the interacting electron gas values and in a metal like Li the nearly free electron theory fails to do this adequately. Knight shift results are summarized, and some attention is given to a recent experiment on the Knight shift of expanded fluid Hg. Difficulties for the theory in relation to transport and the pseudo-gap are pointed out. Finally, new theoretical calculations are reported on the relation between the magnetic properties of the liquid rare earth metals and their electrical conductivity. Mathiessen's rule is shown to break down because of very strong potential scattering. A recent theory of this by Parrinello et al. shows that in the strong scattering limit the magnitude of the localized spin carried by the rare earth ion drops out of the transport theory, as required by the experiments of Güntherodt et al.

Preparation, properties and reactivities of novel platinum compounds containing a thiomethoxymethyl group

Oxidative addition of ClCH 2SCH 3 to PtL 4 afforded trans-PtL 2(CH 2SCH 3)Cl (Ia, L = Ph 3P;Ib, L = MePh 2P). Treatment of I with NH 4PF 6 or Et 3OBF 4 in CH 2C1 2 gave ionic species, [PtL 2(CH 2SCH 3)]X (II, L = Ph 3P, MePh 2P, X = BF 4, PF 6), while similar treatment with MeSO 3F in benzene yielded a new type of stable dimethylsulfonium methylide—platinum complex, trans-[PtL 2(CH 2SMe 2)Cl] SO 3F (IIIa, L = Ph 3P; IIIb, L = MePh 2P). Action of H 2O 2 on Ia gave [Pt(Ph 3P)(μ-CH 2SCH 3)C1] 2 (IV) and its triphenylarsine analog, [Pt(Ph 3As)(μ-CH 2SCH 3)C1] 2 (V) was prepared in one step by oxidative addition of ClCH 2SCH 3 to Pt(AsPh 3) 4. The structural difference between [Pt(Ph 3P)(μ-CH 2SCH 3)C1] 2 and Pd(Ph 3P)- (CH 2SCH 3)C1 is discussed in terms of the difference in the ionization potential from d 10 to d 8 electronic state of metals.

The Electron-Phonon Interaction in Normal Metals

The influence of the electron-phonon many-body renormalization effects on the electron states in normal metals is reviewed. The emphasis is on the electron-phonon mass enhancement parameter λ. The occurrence or absence of renormalization effects is discussed for different electronic properties. After a review of theoretical and experimental methods of obtaining information about λ, numerical values for this quantity are given for the elements. Other sections deal with alloys, compounds, disordered and amorphous metals, anisotropy in λ and variations in λ under pressure. Finally, brief comments are given on the electron-electron and electron-magnon renormalization of the electron mass.

Electronic State of Metal Surface with Random Distribution of Atoms

A formulation is proposed to treat the electronic state of metals with a plane surface on which two kinds of atoms are randomly distributed. The method is a combination of the Kalkstein-Soven theory of :ourface state and the J\1atsubara-Y onezawa cumulant expansion technique. Numerical culculation of partial surface state density is performed for a two­ dimensional model. § l. Introduction Recent development of the techniques in LEED and in producing clean solid surfaces has revealed many interesting phenomena taking place on the surfaces of metals and semi-conductors.n. 2 J For example, reconstruction of the surface layers of metals and rearrangement of the atoms adsorbed on solid surfaces above a certain critical temperature appear to be some sort of phase transition in two dimen­ swn. When the relevant forces between atoms involved in the surface modification are known, we can hope to work out fairly accurate theories for these problems. It seems that there exists an evidence suggesting that the reconstruction or rearrange­ ment of atoms is mediated by some effective long range forces, and thus we are led to a conjecture that surface electronic states may play an important role in such surface phenomena. The theory of surface states has been discussed by many authors making use of two methods. One approach is to extend orthogonalized plane wave and pseudo potential methods to deal -vvith surface states 3

Effect of dispersion on wake-bound electron states in metals

Using a dispersive dielectric function for the response of the electron gas, the induced potential along the path of a fast ion in a metal is calculated. From this, geometrical and binding information for the states of electrons which this potential may bind are determined.

Questions in the electronic state of metals and of the effect of temperature, alloying, and deformation on their state

Questions in the electronic state of metals and of the effect of temperature, alloying, and deformation on their state

Influence of order on electron states in metals

Using the model of independent pseudoatoms, we have obtained the partition function of a random array in terms of a Mayer function determined by the effective potential representing the pseudoatom. This calculation of the partition function is shown to be exact to second order in the scattering potential. It is also correct in the limit of strong, but slowly varying, potentials. To treat the electron states in a liquid metal, built from the same pseudoatom, assumptions have to be made to deal with the three-atom and higher-order correlation functions. Using a simplified form of the Kirkwood approximation the partition function may again be obtained in terms of the same Mayer function as for the random case, plus the two-body correlation function. Results for the partition function are presented for a model of liquid Be. The conclusion is that the partition function for the liquid metal lies quite close to that of the solid, and the short-range order (or excluded volume) appears to be a major factor in determining the electron states. When this order is lost, the partition function changes greatly and the present calculations lead in this case to a very substantial low-energy tail on the density of states. On the other hand, this tail is found to be very small in the liquid metal. Structure in the density of states near the Fermi level, arising from band overlap in the divalent metal, appears to be reduced, but not removed, on melting.

Distribution of electron states in monovalent metals

Abstract A simple prescription is given for calculating densities of states in arbitrary monovalent alloys maintained at fairly arbitrary volumes. In the cases of the pure metals, where comparison with experiment and other theoretical work is possible, satisfactory results are obtained for interpretation of the soft x-ray emission spectra and the Fermi level effective masses. The results are obtained using first-order perturbation theory and non-local pseudopotentials and suggest that non-locality is an essential feature of realistic calculations.

A variational solution for electron states in liquid metals

Abstract Because of irregularities in the Green's function treatment carried to finite order, a variational solution based upon pseudopotentials is sought. The difficulty of orthogonality of the conduction-electron states is circumvented by constructing a many-electron state. The calculation is in close analogy to that of the superconducting ground state. It yields a one-electron energy spectrum and the plane-wave decomposition of the states. Calculations are carried out for a model simple metal and the generalization to transition metals is outlined. Though the perturbation-theoretic irregularities are eliminated and the results appear to be qualitatively correct, the computed corrections to the free-electron curves are smaller than those from the Green's function treatment. It is not clear which is nearer the truth.