This work is devoted to the thermodynamics of high-temperature dense hydrogen plasmas in the pressure region between 10 −1 and 10 2 Mbar. In particular we present for this region results of extensive calculations based on a recently developed path integral Monte Carlo scheme (direct PIMC). This method allows for a correct treatment of the thermodynamic properties of hot dense Coulomb systems. Calculations were performed in a broad region of the nonideality parameter Γ 3 and degeneracy parameter n e Λ 3 10. We give a comparison with a few available results from other path integral calculations (restricted PIMC) and with analytical calculations based on Padé approximations for strongly ionized plasmas. Good agreement between the results obtained from the three independent methods is found.
Strong correlation effects in classical and quantum plasmas are discussed. In particular, Coulomb ͑Wigner͒ crystallization phenomena are reviewed focusing on one-component non-neutral plasmas in traps and on macroscopic two-component neutral plasmas. The conditions for crystal formation in terms of critical values of the coupling parameters and the distance fluctuations and the phase diagram of Coulomb crystals are discussed.
The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principle computer simulations.PACS numbers: 52.27. -h, 52.25.-b Crystallization is one of the most fundamental manyparticle phenomena in charged particle systems. After the prediction of a highly correlated state of the electron gas -the electron Wigner crystal [1] -there has been an active search for this phenomenon in many fields. Crystallization of electrons was observed on the surface of helium droplets [2] and is predicted to occur in semiconductor quantum dots [3]. Moreover, crystals of ions have been observed in traps [4] and storage rings [5], and are expected to occur in layered systems [6]. The necessary condition for the existence of a crystal in these onecomponent plasmas (OCP) is that the mean Coulomb interaction energy, e 2 /r (r denotes the mean inter-particle distance), exceeds the mean kinetic energy (thermal energy 3 2 k B T or Fermi energy E F in classical or quantum plasmas, respectively) by a factor Γ larger than Γ cr which, in a classical OCP is given by 175 [2,7]. In a quantum OCP at zero temperature the coupling strength is measured by the Brueckner parameter, r s ≡r/a B (a B denotes the effective Bohr radius), with a critical value for crystallization of r The vast majority of Coulomb matter in the Universe, however, exists in the form of neutral plasmas, containing (at least) two oppositely charged components (twocomponent plasma, TCP). Coulomb crystallization in a TCP has been observed as well, e.g. in colloidal and dusty plasmas [9,10] and it is predicted to be possible in laser-cooled expanding plasmas [11]. The lattice of heavy particles is immersed into a structureless gas of the light component which does not affect the former. Besides these classical TCP crystals it is expected that in the interior of white dwarf stars and in the crust of neutron stars there exists an entirely different type of TCP crystals [12]: Crystals of highly charged ions (e.g. fully ionized carbon, oxygen, iron) which are embedded into an extremely dense degenerate This Letter aims to answer these questions. We show that, in fact, a common phase diagram of Coulomb crystals in a generic neutral TCP (consisting of electrons and point-like ions [14]) exists which is governed by five parameters -density and temperature (as in the OCP case) and, additionally, by the asymmetry of the heavy (h) and electron (e) components with...
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