[Spglib-users] dataset=None from get_symmetry_dataset()

[Noam B. <noa...@nr...>]

 We’re doing some runs with perhaps slightly weird unit cells (e.g. 11 or 13 atoms), and spglib (via the python interface) occasionally seems to segmentation fault with the following stack trace:
[compute-1-37:10669] *** Process received signal ***
[compute-1-37:10669] Signal: Segmentation fault (11)
[compute-1-37:10669] Signal code: Address not mapped (1)
[compute-1-37:10669] Failing at address: 0x2b5093f547c0
[compute-1-37:10669] [ 0] /lib64/libpthread.so.0[0x3011e0f7e0]
[compute-1-37:10669] [ 1] /usr/local/python/install/python.2.7.10/lib/python2.7/site-packages/spglib/_spglib.so(ptg_get_pointgroup+0x27)[0x2b4c651f7457]
[compute-1-37:10669] [ 2] /usr/local/python/install/python.2.7.10/lib/python2.7/site-packages/spglib/_spglib.so(ref_get_exact_structure_and_symmetry+0xf36)[0x2b4c651f9d86]
[compute-1-37:10669] [ 3] /usr/local/python/install/python.2.7.10/lib/python2.7/site-packages/spglib/_spglib.so(det_determine_all+0x157)[0x2b4c651f0357]
[compute-1-37:10669] [ 4] /usr/local/python/install/python.2.7.10/lib/python2.7/site-packages/spglib/_spglib.so(+0x16273)[0x2b4c651ff273]
[compute-1-37:10669] [ 5] /usr/local/python/install/python.2.7.10/lib/python2.7/site-packages/spglib/_spglib.so(+0x4ff7)[0x2b4c651edff7]
[compute-1-37:10669] [ 6] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5a40)[0x2b4c3fc4dc30]
[compute-1-37:10669] [ 7] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x88e)[0x2b4c3fc4f74e]
[compute-1-37:10669] [ 8] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5b97)[0x2b4c3fc4dd87]
[compute-1-37:10669] [ 9] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x88e)[0x2b4c3fc4f74e]
[compute-1-37:10669] [10] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5b97)[0x2b4c3fc4dd87]
[compute-1-37:10669] [11] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x88e)[0x2b4c3fc4f74e]
[compute-1-37:10669] [12] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x32)[0x2b4c3fc4f862]
[compute-1-37:10669] [13] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyRun_FileExFlags+0xb0)[0x2b4c3fc6f6d0]
[compute-1-37:10669] [14] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(PyRun_SimpleFileExFlags+0xef)[0x2b4c3fc6f8af]
[compute-1-37:10669] [15] /usr/local/python/install/python.2.7.10/lib/libpython2.7.so.1.0(Py_Main+0xc74)[0x2b4c3fc851c4]
[compute-1-37:10669] [16] /lib64/libc.so.6(__libc_start_main+0x100)[0x3011a1ed20]
[compute-1-37:10669] [17] python[0x400649]
[compute-1-37:10669] *** End of error message ***

unfortunately there’s a random number involved and I can’t reproduce the exact run, but when I try, I do get configurations that lead to spglib.get_symmetry_dataset() returning None.  What does that mean (as opposed to group 1, which has no non-identity symmetry operations)?  

I’ll also try to produce a version of spglib with debugging flags on, so I can at least get a more informative stack trace when it happens again.

													Noam