Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis.
Liu, Huiyu; Zhang, Weiguo; Halasyamani, P. Shiv; Stokes, Harold T.; Campbell, Branton J.; Evans, John S. O.; Evans, Ivana Radosavljevic; Journal of the American Chemical Society 140 (2018) 13441–13448; doi:10.1021/jacs.8b08591

data_4133130
_publ_section_title
;
 Understanding the Behavior of the Above-Room-Temperature Molecular
 Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted
 Distortion Mode Analysis.
;
_journal_issue                   41
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              13441
_journal_page_last               13448
_journal_paper_doi               10.1021/jacs.8b08591
_journal_volume                  140
_journal_year                    2018
_chemical_absolute_configuration unk
_chemical_formula_moiety         'C8 H6 Cl2 N2'
_chemical_formula_sum            'C8 H6 Cl2 N2'
_chemical_formula_weight         201.05
_space_group_IT_number           29
_space_group_name_Hall           'P 2c -2ac'
_space_group_name_H-M_alt        'P c a 21'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_H-M   'P c a 21'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   13.9343(3)
_cell_length_b                   5.64024(15)
_cell_length_c                   10.3593(3)
_cell_measurement_reflns_used    0
_cell_measurement_temperature    293
_cell_measurement_theta_max      0
_cell_measurement_theta_min      0
_cell_volume                     814.17(4)
_computing_cell_refinement       'USER DEFINED CELL REFINEMENT'
_computing_data_collection       'USER DEFINED DATA COLLECTION'
_computing_data_reduction        'USER DEFINED DATA REDUCTION'
_computing_molecular_graphics    'CAMERON (Watkin et al., 1996)'
_computing_publication_material  'CRYSTALS (Betteridge et al., 2003)'
_computing_structure_refinement  'CRYSTALS (Betteridge et al., 2003)'
_computing_structure_solution    'SIR92 (Altomare et al., 1994)'
_diffrn_ambient_temperature      293
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.960
_diffrn_measurement_device       Serial
_diffrn_measurement_device_type  Unknown
_diffrn_measurement_method       \w/2\q
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.032
_diffrn_reflns_limit_h_max       20
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1611
_diffrn_reflns_theta_full        29.854
_diffrn_reflns_theta_max         33.543
_diffrn_reflns_theta_min         2.924
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.733
_exptl_absorpt_correction_type   none
_exptl_crystal_density_diffrn    1.640
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             408
_refine_diff_density_max         0.35
_refine_diff_density_min         -0.19
_refine_ls_extinction_method     None
_refine_ls_goodness_of_fit_ref   1.0000
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     133
_refine_ls_number_reflns         1521
_refine_ls_number_restraints     1
_refine_ls_R_factor_all          0.0300
_refine_ls_R_factor_gt           0.0272
_refine_ls_shift/su_max          0.0006540
_refine_ls_shift/su_mean         0.0000326
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
;
 Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982) 
 [weight] = 1.0/[A~0~*T~0~(x)+A~1~*T~1~(x) ... +A~n-1~]*T~n-1~(x)] 
 where A~i~ are the Chebychev coefficients listed below and x= Fcalc/Fmax 
 Method = Robust Weighting (Prince, 1982) 
 W = [weight] * [1-(deltaF/6*sigmaF)^2^]^2^ 
 A~i~ are: 
 0.163E+04 555. 0.148E+04 
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_all         0.0488
_refine_ls_wR_factor_gt          0.0456
_refine_ls_wR_factor_ref         0.0456
_reflns_limit_h_max              20
_reflns_limit_h_min              0
_reflns_limit_k_max              8
_reflns_limit_k_min              0
_reflns_limit_l_max              15
_reflns_limit_l_min              0
_reflns_number_gt                1521
_reflns_number_total             1611
_reflns_threshold_expression     I>2.0\s(I)
_oxford_diffrn_Wilson_B_factor   1.73
_oxford_diffrn_Wilson_scale      0.00
_oxford_refine_ls_r_factor_ref   0.0272
_oxford_refine_ls_scale          9.03(16)
_oxford_reflns_number_all        1606
_oxford_reflns_threshold_expression_ref I>2.0\s(I)
_cod_data_source_file            ja8b08591_si_001.cif
_cod_data_source_block           1
_cod_original_cell_volume        814.16(2)
_cod_original_sg_symbol_H-M      'P c a 21 '
_cod_database_code               4133130