{"id":3121,"date":"2011-01-14T17:53:07","date_gmt":"2011-01-14T15:53:07","guid":{"rendered":"http:\/\/localhost\/azgad\/wordpress\/?p=3121"},"modified":"2011-01-14T21:20:01","modified_gmt":"2011-01-14T19:20:01","slug":"hydrogen-gas-under-pressure-simulations-have-explained-the-peculiar-nature-of-hydrogen-vibration-under-high-pressure","status":"publish","type":"post","link":"https:\/\/azgad.com\/?p=3121","title":{"rendered":"Hydrogen gas: Under pressure – Simulations have explained the peculiar nature of hydrogen vibration under high pressure"},"content":{"rendered":"

.
\n.
\nMost of our Universe consists of hydrogen atoms, which are often found
\nunder extraordinarily high pressure as high as tens of millions of times the
\natmospheric pressure of Earth. Understanding the exotic physics of such
\na high-pressure regime will contribute to our understanding of planet formation,
\nhydrogen storage, room temperature superconductivity and other fields,
\nexplains Toshiaki Iitaka from the RIKEN Advanced Science Institute in Wako.
\n.
\nIitaka, along with colleagues from the Institute of High Performance Computing
\nin Singapore and the University of Saskatchewan in Canada, recently uncovered
\nthe physical basis underlying a newly discovered behavior of hydrogen molecules
\nunder high pressure.
\n.
\n.
\n\"\"<\/a>.
\n.
\n.
\nFigure 1: Traces of the positions of silane and hydrogen molecules over time
\nat 32 GPa, obtained from molecular dynamics calculations. Hydrogen atoms
\nat tetrahedral (white) and octahedral (red) sites are shown. Silicon atoms at
\nso-called \u2018face-centered cubic\u2019 sites are shown by gray spheres
\n.
\n.<\/p>\n

This behavior was observed in a complex of hydrogen molecules, and hydrogen
\nbound to silicon, which is called silane. Silane\u2019s hydrogen atoms are under
\nso-called 'chemical compression' by virtue of their being part of a chemical
\nbond. In 2009, physicists found that the vibrational frequency of hydrogen
\nmolecules in silane\u2013hydrogen complexes fell as the applied pressure rose.
\nThis anti-correlation was the opposite of previous observations of high-pressure
\nhydrogen.
\n.
\nIitaka and colleagues modeled the system using molecular dynamics
\nsimulations. They first optimized the relative arrangement of hydrogen
\nand silane molecules inside a unit cell, finding that the hydrogen molecules
\ntend to sit at octahedral and tetrahedral sites (Fig. 1). They then computed
\nthe vibrational frequencies of the hydrogen molecules, and found two
\ngroups of vibrational modes, one at high energy and one at low energy.
\n.
\nThe frequencies of the lower-energy group decreased monotonically as
\napplied pressure increased. However, the frequencies of the higher-energy
\ngroup increased with pressure until about 20.1 giga Pascals (GPa), after
\nwhich they fell. This reproduced the experimentally observed anti-correlation
\nbetween vibrational frequency and applied pressure, indicating that the
\nsimulation was accurate.
\n.
\nThe simulations also revealed that this rise and fall in frequencies resulted
\nfrom interactions between hydrogen and silane molecules. These
\ninteractions resulted from the overlap between the filled electron orbitals
\nof one molecule and the empty orbitals of the other molecule. This overlap
\nstabilizes the system, and its strength depends on the distance between
\nthe molecules. This distance, in turn, depends on the applied pressure.
\n.
\nThe simulation results are another glimpse into the exotic physics that
\nunderpins the high-pressure regime, according to Iitaka. \u201cWe have shown
\nthat there is much more interesting new physics and chemistry to be explored
\nin the world of high pressure.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

. . Most of our Universe consists of hydrogen atoms, which are often found under extraordinarily high pressure as high as tens of millions of times the atmospheric pressure of Earth. Understanding the exotic physics of such a high-pressure regime will contribute to our understanding of planet formation, hydrogen storage, room temperature superconductivity and other … <\/p>\n

\u05d4\u05de\u05e9\u05d9\u05db\u05d5 \u05d1\u05e7\u05e8\u05d9\u05d0\u05d4<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[10],"tags":[513,114,49],"class_list":["post-3121","post","type-post","status-publish","format-standard","hentry","category-10","tag-513","tag-114","tag-49","nodate","item-wrap"],"_links":{"self":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3121","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3121"}],"version-history":[{"count":7,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3121\/revisions"}],"predecessor-version":[{"id":3132,"href":"https:\/\/azgad.com\/index.php?rest_route=\/wp\/v2\/posts\/3121\/revisions\/3132"}],"wp:attachment":[{"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3121"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3121"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/azgad.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3121"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}