Miguel Martinez-Canales

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High-pressure structures of germane (GeH4) are explored through ab initio evolutionary methodology to reveal a metallic monoclinic structure of C2/c (4 molecules/cell). The C2/c structure consists of layerlike motifs containing novel "H2" units. Enthalpy calculations suggest a remarkably wide decomposition (Ge+H2) pressure range of 0-196 GPa, above which(More)
Following the suggestion that hydrogen-rich compounds, and, in particular, silane (SiH4), might be high-T_{c} superconductors at moderate pressures, very recent experiments have confirmed that silane metallises and even becomes superconducting at high pressure. In this article, we present a structural characterization of compressed silane obtained with an(More)
Computational searches for stable and metastable structures of water ice and other H:O compositions at TPa pressures have led us to predict that H(2)O decomposes into H(2)O(2) and a hydrogen-rich phase at pressures of a little over 5 TPa. The hydrogen-rich phase is stable over a wide range of hydrogen contents, and it might play a role in the erosion of the(More)
Phases of carbon are studied up to pressures of 1 petapascal (PPa) using first-principles density-functional-theory methods and a structure searching algorithm. Our extensive search over the potential energy surface supports the sequence of transitions diamond → BC8 → simple cubic under increasing pressure found in previous theoretical studies. At higher(More)
Computational searches for structures of solid oxygen under high pressures in the multi-TPa range are carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into a semiconducting square-spiral-like polymeric structure (I4(1)/acd) with a band gap of ~3.0 eV. Solid oxygen forms a(More)
The phase diagram and equation of state of dense nitrogen are of interest in understanding the fundamental physics and chemistry under extreme conditions, including planetary processes, and in discovering new materials. We predict several stable phases of nitrogen at multi-TPa pressures, including a P4/nbm structure consisting of partially charged N(2)(δ+)(More)
The crystal structure of elements at zero pressure and temperature is the most fundamental information in condensed matter physics. For decades it has been believed that lithium, the simplest metallic element, has a complicated ground-state crystal structure. Using synchrotron x-ray diffraction in diamond anvil cells and multiscale simulations with density(More)
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