Hempler Daniela, Schmidt Martin U, van de Streek Jacco
Institute of Inorganic and Analytical Chemistry, Goethe University, Max-von-Laue-Strasse 7, Frankfurt am Main, 60438, Germany.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2017 Aug 1;73(Pt 4):756-766. doi: 10.1107/S2052520617005935. Epub 2017 Jul 25.
More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic coordinates of all non-H atoms is established to be 0.2 Å. For 98.5% of 200 molecular crystal structures published with missed symmetry, the correct space group is identified; there are no false positives. Very small, very symmetrical molecules can end up in artificially high space groups upon energy minimization, although this is easily detected through visual inspection. If the space group of a crystal structure determined from powder diffraction data is ambiguous, energy minimization with DFT-D provides a fast and reliable method to select the correct space group.
利用色散校正密度泛函理论（DFT-D，PBE-D3）对600多个具有正确、错误和不确定空间群对称性的分子晶体结构进行了能量最小化处理。为了确定正确的空间群对称性，将所有非氢原子的原子坐标所需的公差设定为0.2 Å。对于已发表的200个对称性缺失的分子晶体结构，98.5%的结构确定了正确的空间群；没有误判为正确的情况。非常小且非常对称的分子在能量最小化后可能会出现人为的高空间群情况，不过通过目视检查很容易检测到。如果由粉末衍射数据确定的晶体结构的空间群不明确，使用DFT-D进行能量最小化可提供一种快速可靠的方法来选择正确的空间群。
