Importance of the consideration of anharmonic motion in charge-density studies: a comparison of variable-temperature studies on two explosives, RDX and HMX
Zhurov, Vladimir V.; Zhurova, Elizabeth A.; Stash, Adam I.; Pinkerton, A. Alan; Acta Crystallographica Section A Foundations of Crystallography 67 (2011) 160–173; doi:10.1107/S0108767310052219

data_2019354
_publ_section_title
;
 Importance of the consideration of anharmonic motion in charge-density
 studies: a comparison of variable-temperature studies on two explosives,
 RDX and HMX
;
_journal_issue                   2
_journal_name_full
'Acta Crystallographica Section A Foundations of Crystallography'
_journal_page_first              160
_journal_page_last               173
_journal_paper_doi               10.1107/S0108767310052219
_journal_volume                  67
_journal_year                    2011
_chemical_formula_moiety         'C3 H6 N6 O6 '
_chemical_formula_sum            'C3 H6 N6 O6'
_chemical_formula_weight         222.14
_space_group_IT_number           61
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2ac 2ab'
_symmetry_space_group_name_H-M   'P b c a'
_atom_type_scat_source           'Volkov et al, (2006)'
_cell_angle_alpha                90.000
_cell_angle_beta                 90.000
_cell_angle_gamma                90.000
_cell_formula_units_Z            8
_cell_length_a                   11.3790(2)
_cell_length_b                   10.5694(2)
_cell_length_c                   13.1314(2)
_cell_measurement_reflns_used    120142
_cell_measurement_temperature    20.0(1)
_cell_measurement_theta_max      69.98
_cell_measurement_theta_min      3.055
_cell_volume                     1579.30(5)
_computing_cell_refinement       'Otwinowski & Minor (1997)'
_computing_data_collection       CrystalClear,(2005)
_computing_data_reduction        'Zhurov et al,(2005)'
_computing_molecular_graphics    'Volkov et al, (2006)'
_computing_publication_material  'Volkov et al, (2006)'
_computing_structure_refinement  'Volkov et al, (2006)'
_computing_structure_solution    'Sheldrick (1997)'
_diffrn_ambient_temperature      20.0(1)
_diffrn_measured_fraction_theta_full 1.0
_diffrn_measured_fraction_theta_max 0.70
_diffrn_measurement_device       'Rigaku R-axis Rapid'
_diffrn_measurement_method       w
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0191
_diffrn_reflns_limit_h_max       28
_diffrn_reflns_limit_h_min       -28
_diffrn_reflns_limit_k_max       21
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       34
_diffrn_reflns_limit_l_min       -34
_diffrn_reflns_number            120142
_diffrn_reflns_theta_full        28.28
_diffrn_reflns_theta_max         69.98
_exptl_absorpt_coefficient_mu    0.178
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.868
_exptl_crystal_description       'pyramid '
_exptl_crystal_F_000             912.0
_exptl_crystal_size_max          0.23
_exptl_crystal_size_mid          0.23
_exptl_crystal_size_min          0.23
_refine_diff_density_max         0.19
_refine_diff_density_min         -0.17
_refine_ls_extinction_coef       0.0
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.90
_refine_ls_hydrogen_treatment    refall
_refine_ls_number_parameters     754
_refine_ls_number_reflns         8057
_refine_ls_R_factor_gt           0.0145
_refine_ls_shift/su_max          0.0000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;    calc w2 = q/[s^2^(Fo^2^) + (0.006 P)^2^ + 0.008 P + 0.00 + 0.00 sin(th)]
     where P = (1.0000 Fo^2^ + 0.0000 Fc^2^)
           q = 1.0
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.0104
_reflns_number_gt                8057
_reflns_number_total             10651
_reflns_threshold_expression
'I>3\s, non-overlapped & non-partial reflections'
_cod_data_source_file            sh5121sup1.cif
_cod_data_source_block           RDX20KAnharmonic
_cod_depositor_comments
;
The following automatic conversions were performed:

'_symmetry_cell_setting' value 'Orthorhombic' changed to
'orthorhombic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 1891 2012-01-12 08:04:46Z andrius 
;
_cod_original_sg_symbol_H-M      Pbca
_cod_original_formula_sum        'C3 H6 N6 O6 '
_cod_database_code               2019354
_atom_site_anharm_details
;
The atomic anharmonic pdf is approximated by a Gram-Charlier expansion
about the harmonic pdf, according to the expression :
 
      P(u) = (1 + Cijk*Hijk/3! + Dijkl*Hijkl/4!)*P(0)
 
The coefficients Cijk and Dijkl are refined in the least squares procedure.
The reported coefficients Cijk are multiplied by 1000 and Dijkl by 10000.
;