The charge density of urea from synchrotron diffraction data
Birkedal, Henrik; Madsen, Dennis; Mathiesen, Ragnvald H.; Knudsen, Kenneth; Weber, Hans-Peter; Pattison, Philip; Schwarzenbach, Dieter; Acta Crystallographica Section A Foundations of Crystallography 60 (2004) 371–381; doi:10.1107/S0108767304015120

data_2019369
_publ_section_title
;
 The charge density of urea from synchrotron diffraction data
;
_journal_issue                   5
_journal_name_full
'Acta Crystallographica Section A Foundations of Crystallography'
_journal_page_first              371
_journal_page_last               381
_journal_paper_doi               10.1107/S0108767304015120
_journal_volume                  60
_journal_year                    2004
_chemical_formula_moiety         'C H4 N2 O'
_chemical_formula_sum            'C H4 N2 O'
_chemical_formula_weight         60.06
_chemical_name_common            urea
_space_group_IT_number           113
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  'P -4 2ab'
_symmetry_space_group_name_H-M   'P -4 21 m'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_atom_type_scat_source
;
Charge density refinement.
;
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   5.5780(6)
_cell_length_b                   5.5780(6)
_cell_length_c                   4.6860(7)
_cell_measurement_reflns_used    17
_cell_measurement_temperature    123(2)
_cell_volume                     145.80(3)
_computing_cell_refinement       'KM6-CH software'
_computing_data_collection       'KM6-CH software'
_computing_data_reduction        XD_RED
_computing_structure_refinement  VALRAY
_diffrn_ambient_temperature      123(2)
_diffrn_measured_fraction_theta_full 0.938
_diffrn_measured_fraction_theta_max 0.938
_diffrn_measurement_device_type
;
KM6-CH six-circle \k diffractometer operated as standard four-circle
\k diffractometer with detector circle in the vertical plane to profit
from the linear polarization of the synchrotron beam.
;
_diffrn_measurement_method       \w-scan
_diffrn_radiation_monochromator  'Si(111) double crystal monochromator'
_diffrn_radiation_source         'bending magnet'
_diffrn_radiation_type           synchrotron
_diffrn_radiation_wavelength     0.59960(10)
_diffrn_reflns_av_R_equivalents  0.0141
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       0
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       0
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            3942
_diffrn_reflns_theta_full        59.82
_diffrn_reflns_theta_max         59.82
_diffrn_reflns_theta_min         3.67
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.368
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             64
_exptl_crystal_size_max          0.23
_exptl_crystal_size_mid          0.13
_exptl_crystal_size_min          0.09
_refine_ls_extinction_coef       '0.0000016(3) rad^2'
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.1661
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     77
_refine_ls_number_reflns         1045
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.1661
_refine_ls_R_factor_all          0.0204
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details     w=1/[\s^2^(Fo^2]
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.0104
_reflns_number_gt                817
_reflns_number_total             1045
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            xc5013sup1.cif
_cod_data_source_block           I
_cod_database_code               2019369