Urea
      Swaminathan S, Craven B M
      Acta Crystallographica B40 (1984) 300-306
      The crystal structure and molecular thermal motion of urea
      at 12, 60 and 123 K from neutron diffraction
      Note: neutron data, T = 12 K
      Locality: synthetic
      _database_code_amcsd 0020674

      CELL PARAMETERS:    5.5650   5.5650   4.6840   90.000   90.000   90.000
      SPACE GROUP: P-42_1m   
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:    145.060
      Density (g/cm3):      1.375
      MAX. ABS. INTENSITY / VOLUME**2:      9.806597675    
      RIR:      2.323
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                22.60        100.00        3.9350    1   1   0         4
                24.85         22.24        3.5836    1   0   1         8
                29.65         28.65        3.0129    1   1   1         4
                32.17          6.34        2.7825    2   0   0         4
                36.09         15.19        2.4887    2   1   0         8
                37.60         12.50        2.3922    2   0   1         8
                38.44          1.58        2.3420    0   0   2         2
                41.07          5.05        2.1978    2   1   1         8
                41.85          6.58        2.1586    1   0   2         8
                45.05          2.15        2.0125    1   1   2         4
                46.14          5.90        1.9675    2   2   0         4
                50.30          6.70        1.8140    2   2   1         4
                53.10          3.05        1.7247    3   0   1         8
                53.74          1.66        1.7056    2   1   2         8
                55.80          7.83        1.6474    3   1   1         8
                61.56          1.26        1.5065    2   2   2         4
                61.70          1.63        1.5033    1   0   3         8
                70.63          1.83        1.3337    4   0   1         8
                71.31          2.48        1.3226    2   1   3         8
                71.99          2.40        1.3117    3   3   0         4
                76.56          1.56        1.2444    4   2   0         8
                82.61          1.83        1.1679    3   1   3         8
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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.