update the doc to support the display of optimize module

doc/requirements.txt

@@ -7,3 +7,4 @@ scipy>=1.7.3
 importlib_metadata>=1.4
 ase>=3.18.0
 sphinx_rtd_theme
+pyocse>=0.1.1

pyxtal/db.py

@@ -1343,6 +1343,7 @@ def export_structures(
                 status = xtal.check_validity(criteria, True) if criteria is not None else True
             except:
                 status = False
+                label = "Error"
 
             if status:
                 try:
@@ -1352,10 +1353,9 @@ def export_structures(
                         _l, _sp, _cn = s.wp.get_label(), s.specie, s.coordination
                         label += f"-{_l:s}-{_sp:s}{_cn:d}"
                     label += f"-S{sim:.3f}"
+                    if len(label) > 40: label = label[:40]
                 except:
                     print("Problem in setting site coordination")
-                if len(label) > 40:
-                    label = label[:40]
 
                 if den is not None:
                     label += f"-D{abs(den):.2f}"

setup.py

@@ -70,6 +70,7 @@ def run(self):
         "vasprun-xml>=1.0.4",  # prevent the use of numpy2
         "importlib_metadata>=1.4",
         "typing-extensions>=4.12",
+        "pyocse>=0.1.1",
     ],
     extras_require={
         "visualization": ["py3Dmol>=0.8.0"],