Incorrect site symmetry symbol for some Wyckoff sites

[kazeevn]

Hello!

pyXtal reports that Wyckoff sites f and e in group 150 have site symmetry 1. International Tables for Crystallography (2016). Vol. A, ch. 2.3, Space group 150. lists site symmetry as .2.; another source.

>>> from pyxtal import Group
>>> Group(150)
-- Spacegroup --# 150 (P321)--
6g	site symm: 1
3f	site symm: 1
3e	site symm: 1
2d	site symm: 3..
2c	site symm: 3..
1b	site symm: 32.
1a	site symm: 32.

Version: latest commit e086219

[kazeevn]

And some more:

{
150: {
    "f": ".2.",
    "e": ".2."},
152: {
    "a": ".2.",
    "b": ".2."},
154: {
    "a": ".2.",
    "b": ".2."},
155: {
    "e": ".2",
    "d": ".2"},
164: {
    "g": ".2.",
    "h": ".2."},
165: {
    "f": ".2."},
166: {
    "f": ".2",
    "g": ".2"},
167: {
    "e": ".2"
},
177: {
    "j": ".2.",
    "k": ".2."},
178: {
    "a": ".2."
},
179: {
    "a": ".2."
},
180: {
    "g": ".2.",
    "h": ".2."},
181: {
    "g": ".2.",
    "h": ".2."},
182: {
    "g": ".2."},
190: {
    "g": ".2."},
191: {
    "o":  ".m."},
192: {
    "j": ".2."},
194: {
    "i": ".2.",
    "k": ".m."}
}

[qzhu2017]

This is related to the interpretation of site symmetry class. Needs to look it again.

[qzhu2017]

@kazeevn I think this bug has been fixed after my commits today.

Can you try to run the updated code from the master branch with more examples?

I will close this issue after getting a green light from you.

[kazeevn]

I found the problem by discovering that some Wyckoff positions with the same symmetry had different multiplicity, this is no longer that case: check_site_symmetry.py.gz, the problem is fixed as far as I can tell. Thank you!