Platinum metal was shock compressed to 660 GPa using a two-stage light-gas gun qualify this material as an ultrahigh-pressure standard for both dynamic and static experiments. The velocity data are consistent with most of the previously measured low-pressure data, overall linear us−up relationship is found over range 32–660 GPa. As part work, we have also extended Hugoniot tantalum use 560 GPa; included these into new fit between 55–560 We present results first-principles theoretical...

We have developed an empirical EAM potential for magnesium by fitting to ab initio forces (the `force matching' method) and experimental data. The database includes many different structures, including bulk, cluster, liquid several defect structures. fit the database, which has 2201 generated using a local orbital pseudopotential method, is good. This new gives good results various bulk structural properties.

Ab initio electronic-structure calculations, based on density-functional theory and a full-potential linear-muffin-tin-orbital method, have been used to predict crystal-structure phase stabilities, elastic constants, Brillouin-zone-boundary phonons for iron under compression. Total energies five crystal structures, bcc, fcc, bct, hcp, dhcp, calculated over wide volume range. In agreement with experiment previous theoretical magnetic bcc ground state is obtained at ambient pressure...

New shock compression data for Al, Cu, and Pb in the pressure range 0.3--1 TPa (3--10 Mbar) have been combined with first-principles theory earlier equation-of-state to give first self-consistent description of thermodynamic states metals at ultrahigh pressures. No evidence is found a break slope Hugoniot Al near 0.5 TPa, as claimed by Al'tshuler.

Extensive phase-stability calculations for the fcc, hcp, and bcc structures of Na, Mg, Al, Si are reported both near 1 atm under high pressure, where becomes a natural member this set third-period simple metals Calculations each element have been carried out by two entirely different first-principles techniques: generalized pseudopotential theory (GPT) linear-muffin-tin orbitals (LMTO) method. The techniques give results in good qualitative agreement Si, predict sequences high-pressure...

We present acoustic velocity data that demonstrate a high-pressure solid-solid phase transition in molybdenum at about 2.1 Mbar and 4100 K. This observation is supported here by first-principles theoretical calculations which predict zero-temperature bcc\ensuremath{\rightarrow} hcp within our experimental pressure range. In addition, results show the melting for shock-compressed Mo 3.9 10000

The first-principles, density-functional version of the generalized pseudopotential theory (GPT) developed in papers I and II this series [Phys. Rev. B 16, 2537 (1977); 26, 1754 (1982)] for empty- filled-d-band metals is here extended to pure transition with partially filled d bands. present focus on a rigorous, real-space expansion bulk total energy terms widely transferable, structure-independent interatomic potentials, including both central-force pair interactions angular-force triplet...

The first-principles, density-functional version of the generalized pseudopotential theory (GPT), previously developed for empty- and filled-d-band metals, recently has been extended to pure transition metals with partially filled d bands [Phys. Rev. B 38, 3199 (1988)]. Within this formalism, a rigorous real-space expansion bulk total energy obtained in terms widely transferable, structure-independent interatomic potentials, including both central-force pair interactions angular-force...

The pseudopotential theory of $d$-band metals discussed by the author in a previous paper is used to consider total energy noble metals. theoretical total-energy calculation completed adding electronic direct electrostatic repulsion between ions and subtracting from it an equal electron-electron interaction. result expressed as sum four quantities: free-electron energy, band-structure (or Ewald) overlap energy. first three are directly analogous usual quantities found simple-metal fourth...

Using the generalized pseudopotential formalism given by Harrison, form factors have been calculated for copper, silver, and gold at both liquid solid densities. All quantities entering in from first principles, including position of $d$ resonance. The full nonlocal character ordinary terms additional hybridization is included without approximation. To order, orthogonalization hole has also treated exactly. Kohn-Sham approximation used conduction band-core exchange, while exchange among...

Equation-of-state data and corresponding first-principles theory for the metals Al, Cu, Mo, Pb are reported over shock pressure range 0.4–2.4 TPa (4–24 Mbar). Strong waves were generated by nuclear explosions a two-stage light-gas gun. The experimental occur in hot liquid-metal regime, where condensed-matter applies but with unusually large thermal components to equation of state.

First-principles total-energy calculations by two independent methods predict new transition-metal-like sequences of stable crystal structures in the third-period simple metals Na, Mg, and Al, under increasing pressure. These structural phase transitions are controlled $d$ electrons through lowering partial filling initially empty $3d$ band as compressed. A number these occur megabar range below could be investigated existing experimental techniques.

The density-functional formulation of the generalized pseudopotential theory (GPT) set forth in paper I this is recast an optimum representation and more widely applied to empty- filled-$d$-band metals. Optimization achieved by making most advantageous separation possible (i) hybridization potential into volume-dependent (${\ensuremath{\Delta}}_{\mathrm{vol}}$) structure-dependent (${\ensuremath{\Delta}}_{\mathrm{struc}}$) parts, (ii) nonuniform component valence-electron density screening...

We present an overview of recent work on quantum-based atomistic simulation materials properties in transition metals performed the Metals and Alloys Group at Lawrence Livermore National Laboratory. Central to much this effort has been development, from fundamental quantum mechanics, robust many-body interatomic potentials for bcc via model generalized pseudopotential theory (MGPT), providing close linkage between ab initio electronic-structure calculations large-scale static dynamic...

Using multi-ion interatomic potentials derived from first-principles generalized pseudopotential theory, we have studied ideal shear strength, point defects, and screw dislocations in the prototype bcc transition metal molybdenum (Mo). Many-body angular forces, which are important to structural mechanical properties of such central metals with partially filled d bands, accounted for present theory through explicit three- four-ion potentials. For strength Mo, our computed results agree well...

The method of matched asymptotic expansions is used to solve for the free surface a thin liquid drop draining down vertical wall under gravity. analysis based on smallness tension term in lubrication equation. In region local front drop, where curvature large, forces are significant. Everywhere else, small, and plays negligible role. A numerical time-marching scheme, which makes no small assumptions, developed provide datum from gauge accuracy theory. Agreement between scheme theory good...

Using multi-ion interatomic potentials derived from first-principles generalized pseudopotential theory (GPT) together with molecular-dynamics (MD) simulation, a detailed study of melting and related high-temperature solid liquid properties in molybdenum has been performed. The energetics such bcc transition metals are dominated by d-state interactions that give rise to both many-body angular forces enhanced electron-thermal contributions. accounted for the GPT through explicit three-...

Percutaneous interstitial microwave thermoablation of locally recurrent prostate carcinoma was continually guided with magnetic resonance (MR) imaging. Phase images and data were obtained a rapid gradient-echo technique used to derive tissue temperature change on the basis proton-resonance shift. Thermally devitalized regions correlated well phase image findings. MR imaging-derived temperatures linearly related fluoroptic temperatures. imaging can be guide thermoablation.

A detailed theoretical study of the A1 melting curve from normal conditions to pressures in vicinity 2 Mbar is presented. The analysis based on two parallel, but distinct, treatments metal: first rigorous generalized pseudopotential theory involving first-principles nonlocal pseudopotentials and second a parametrized local model which has been accurately fit band-theory experimental equation-of-state data. Both utilize full lattice-dynamical calculations phonon free energy solid, within...

The generalized pseudopotential theory of $d$-band metals is rederived using the self-consistent-field equations Kohn and Sham as starting point. basic features original are recovered, but a number important unifying refinements achieved. Central to development careful approximation total exchange correlation potential in form constant plus sum overlapping, structure-independent, intra-atomic potentials. This result, combined with our previously introduced zero-order-pseudoatom technique...

Phase diagrams of refractory metals remain essentially unknown. Moreover, there is an ongoing controversy over the high-pressure melting temperatures these metals: results diamond anvil cell (DAC) and shock wave experiments differ by at least a factor 2. From extensive ab initio study on tantalum we discovered that body-centered cubic phase, its physical phase ambient conditions, transforms to another solid possibly hexagonal omega high temperature. Hence sample motion observed in DAC very...

A general one-electron pseudo-Green's-function formalism is developed as an extension of the true-Green's-function techniques Anderson. Pseudo-Green's-function equations are derived in arbitrary, overcomplete basis representation for a non-Hermitian pseudo-Hamiltonian. The flexibility choice both set and pseudopotential makes method useful treating variety physical systems. Formal calculations pseudo Green's function density states considered simple metals well $d$-band metals. applied...

Fundamental high-pressure structural and mechanical properties of Ta have been investigated theoretically over a wide pressure range, 0$\ensuremath{-}$10 Mbar, by means ab initio electronic-structure calculations. The calculations are fully relativistic use state-of-the-art treatment gradient corrections to the exchange-correlation potential energy within density-functional theory. calculated zero-temperature equation state for bcc is in good agreement with diamond-anvil-cell measurements up...

Monovacancies for seven bcc d-transition metals V, Cr, Fe, Nb, Mo, Ta, and W have been studied in detail from first-principles calculations. A full-potential, linear muffin-tin-orbital (FP-LMTO) method has used conjunction with both the local-density approximation (LDA) generalized-gradient (GGA) to calculate volume-relaxed vacancy formation energies all metals. complementary ab initio pseudopotential (PP) volume- structure-relaxed LDA volumes W. Fully relaxed PP geometries also applied...

Abstract The fundamental atomic-level properties of (a/2)(111) screw dislocations and other defects in bcc Ta have been simulated by means new quantum-based multi-ion interatomic potentials derived from the model generalized pseudopotential theory (MGPT). validated detail using a combination experimental data ab-initio electronic structure calculations on ideal shear strength, vacancy self-interstitial formation migration energies, grain-boundary atomic stacking-fault energy (γ) surfaces....