[BUG] the coords can't be identified when read_from gaussian log file

[Zhang-Zhiyuan-zzy]

At present, the plugin reading gaussian log file identifies the coords context by title: "Z-Matrix orientation:" and "Input orientation:". In general, it works fine. However, the log file, sometimes, might only record the "Standard orientation:" coords. In the case, the coords can't be localized by the current plugin and will raise the UnboundLocalError.

The following the bug-raised code:

import dpdata
ls = dpdata.LabeledSystem('pair_3.log', fmt='gaussian/md')

The error message:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/system.py", line 281, in __init__
    self.from_fmt(
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/system.py", line 318, in from_fmt
    return self.from_fmt_obj(load_format(fmt), file_name, **kwargs)
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/system.py", line 1162, in from_fmt_obj
    data = fmtobj.from_labeled_system(file_name, **kwargs)
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/plugins/gaussian.py", line 23, in from_labeled_system
    return GaussianLogFormat().from_labeled_system(file_name, md=True)
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/plugins/gaussian.py", line 15, in from_labeled_system
    return dpdata.gaussian.log.to_system_data(file_name, md=md)
  File "/home/pub/conda3/envs/hpu/lib/python3.9/site-packages/dpdata/gaussian/log.py", line 49, in to_system_data
    coords_t.append(coords)
UnboundLocalError: local variable 'coords' referenced before assignment

The system and envoriments:

• Operate System: Ubuntu 22.04 lts
• Python: 3.9.0
• dpdata version: 0.2.15

This error can be resolved by making a little modification to a portion of the code:

1. Add a new conditional branch to recognize "Standard orientation:"
2. read the Standard coordinates when meet the flag == 16

The modified code like the following (The modified have been marked by '# TODO: Modified'). This modification would not make changes for the general case, where the "input orientation:" or "Z-Matrix orientation:" is in the text, because of the "Input orientation:" and "Z-Matrix orientation:" are always on the above of "Standard orientation:"

The above modification has been tested on my machine and works fine in both the general case and the bug-raised case.

May I request to make a modification to that portion of the code?