Fix issue #517 (#520)

Co-authored-by: Han Wang <wang_han@iapcm.ac.cn>

Author: wanghan-iapcm

dpdata/qe/traj.py

@@ -205,6 +205,7 @@ def to_system_data(input_name, prefix, begin=0, step=1):
         data["cells"], tmp_steps = load_data(
             prefix + ".cel", 3, begin=begin, step=step, convert=length_convert
         )
+        data["cells"] = np.transpose(data["cells"], (0, 2, 1))
         if csteps != tmp_steps:
             csteps.append(None)
             tmp_steps.append(None)

tests/qe.traj/traj6.cel

@@ -1,24 +1,24 @@
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