# Finding cubic ice CIF files in crystal database

Could anyone please tell me where I could find the the structure of cubic ice (ice Ic) as a CIF file?

I have been searching the cambridge structural database using "H2O", "water", "dihyrogen oxide" and "ice" as search key words, but cannot find anything!

• I don't have access to CCSD from home. Sounds more like a problem in how you're searching. Nevertheless, ICSD has it. If you perform an advanced search "Structure Type" search, it's "H2O(Ic)" as a pre-defined structure. There should be a few hits. Jun 18, 2015 at 3:14
• Ok, thanks. I did that, but it doesn't look like any of the files have the hydrogens attached. Do you know where I could find the file with the hydrogens included? One of the files ( Neutron-diffraction study of ice polymorphs. III. Ice Ic) seems to have three hydrogens attached to each oxygen. Jun 18, 2015 at 18:05
• CCSD is probably wrong place for the search. It's organic DB, e.g. the molecule should have at least one C-H bond. Of course there are some exceptions but you will not find a lot of unsubstituted-boranes there either. Aug 27, 2015 at 9:41

One resource you can use is the Crystallography Open Database. Search for structures with two elements O and H, and named “ice”. You will then find several experimental structures for cubic ice:

with downloadable structure files in CIF format: 1, 2. These were done from X-ray diffraction studies and only feature heavy atoms (oxygen) positions.

Although I could not find in any open database a CIF file for cubic ice with hydrogen positions, it is easy to make one. From the paper “High-resolution neutron powder diffraction study of ice Ic”, Le Journal de Physique Colloques, 48.C1 (1987), C1-631:

you can create the CIF file yourself:

data_Ice_Ic
_audit_creation_method         'generated by CrystalMaker 9.2.7'
_publ_section_comment
;
Chemical formula (sum): H2 O

Systematic name: H2 O

Crystal structure data from: W.F. Kuhs, D.V. Bliss, J.L. Finney,  High-resolution neutron powder diffraction study of ice Ic, Journal de Physique Colloques, 1987, 48, C1-631

;
_cell_length_a                   6.358(3)
_cell_length_b                   6.358(3)
_cell_length_c                   6.358(3)
_cell_angle_alpha               90.000(0)
_cell_angle_beta                90.000(0)
_cell_angle_gamma               90.000(0)

_symmetry_space_group_name_H-M     'F 41/d -3 2/m'
_symmetry_Int_Tables_number         227
_symmetry_cell_setting             cubic
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loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_occupancy
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
H1    H  0.5000      0.4670(19) 0.4670(19)  0.4670(19)
O1    O  1.0000      0.3750     0.3750      0.3750

• If you see the subsequent comment, this actually didn't answer the OP question - the files in the COD don't place the hydrogens, only the oxygens. To my knowledge, there are no open CIF files for cubic ice with hydrogens present. Aug 9, 2016 at 15:11
• @GeoffHutchison but protons are disordered in cubic ice… so if you had hydrogens present they wouldn't be in crystallographic sites with full occupancy anyway
– F'x
Aug 9, 2016 at 15:15
• Indeed. I remember some sort of chat with the OP, since CCSD does have a neutron-diffraction structure with disordered protons (and IIRC the occupancies?). That was sufficient once the occupancies were clarified, but the COD structure was problematic, since you have to guess O-H bond lengths and occupancies. Aug 9, 2016 at 15:19
• @GeoffHutchison I've made a CIF file from a 1987 neutron paper, and I've added it to the answer, in case it can help someone in the future
– F'x
Aug 9, 2016 at 16:29