Hydrogen
      Mao H K, Jephcoat A P, Hemley R J, Finger L W, Zha C S, Hazen R M, Cox D E
      Science 239 (1988) 1131-1133
      Synchrotron X-ray diffraction measurements of single-crystal hydrogen to
      26.5 Gigapascals
      Locality: synthetic
      Sample: at P = 21.4 GPa, T = 300 K
      _database_code_amcsd 0015435

      CELL PARAMETERS:    2.3080   2.3080   3.7030   90.000   90.000  120.000
      SPACE GROUP: P6_3/mmc  
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:     17.083
      Density (g/cm3):      0.196
      MAX. ABS. INTENSITY / VOLUME**2:     0.6530130398E-01
      RIR:      0.109
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                45.37         36.93        1.9988    1   0   0         6
                49.21         30.89        1.8515    0   0   2         2
                51.99        100.00        1.7589    1   0   1        12
                69.16          5.23        1.3583    1   0   2        12
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       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.