Fix swapped arithmetic crystal class numbers for space groups 187-190

CHANGELOG.md

@@ -6,6 +6,12 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 Unlisted patch versions (e.g. v0.7.1, v0.7.3, v0.7.6, v0.7.7) contain only dependency or build updates with no user-visible changes.
 
+## Unreleased
+
+### moyo
+
+- Fix swapped arithmetic crystal class numbers 56 and 57 for space groups 187-190: `-6m2P` is No. 56 and `-62mP` is No. 57 per International Tables for Crystallography, Volume C (2004), Table 1.4.2.1. The symbols reported for these space groups were already correct; only the numbers exposed via `MoyoDataset` and `moyopy.SpaceGroupType.arithmetic_number` change. Same fix as spglib/spglib#632 (#398)
+
 ## v0.14.0 - 2026-07-04
 
 ### moyo

moyo/src/data/arithmetic_crystal_class.rs

@@ -110,8 +110,8 @@ const ARITHMETIC_CRYSTAL_CLASS_DATABASE: [ArithmeticCrystalClassEntry; 73] = [
     ArithmeticCrystalClassEntry::new(53, "6/mP", GeometricCrystalClass::C6h, BravaisClass::hP),
     ArithmeticCrystalClassEntry::new(54, "622P", GeometricCrystalClass::D6, BravaisClass::hP),
     ArithmeticCrystalClassEntry::new(55, "6mmP", GeometricCrystalClass::C6v, BravaisClass::hP),
-    ArithmeticCrystalClassEntry::new(56, "-62mP", GeometricCrystalClass::D3h, BravaisClass::hP),
-    ArithmeticCrystalClassEntry::new(57, "-6m2P", GeometricCrystalClass::D3h, BravaisClass::hP),
+    ArithmeticCrystalClassEntry::new(56, "-6m2P", GeometricCrystalClass::D3h, BravaisClass::hP),
+    ArithmeticCrystalClassEntry::new(57, "-62mP", GeometricCrystalClass::D3h, BravaisClass::hP),
     ArithmeticCrystalClassEntry::new(58, "6/mmmP", GeometricCrystalClass::D6h, BravaisClass::hP),
     // Crystal system: cubic
     ArithmeticCrystalClassEntry::new(59, "23P", GeometricCrystalClass::T, BravaisClass::cP),

moyo/src/data/hall_symbol_database.rs

@@ -3874,7 +3874,7 @@ static HALL_SYMBOL_DATABASE: [HallSymbolEntry; 530] = [
     HallSymbolEntry::new(
         481,
         187,
-        57,
+        56,
         "",
         "P -6 2",
         "P -6 m 2",
@@ -3884,7 +3884,7 @@ static HALL_SYMBOL_DATABASE: [HallSymbolEntry; 530] = [
     HallSymbolEntry::new(
         482,
         188,
-        57,
+        56,
         "",
         "P -6c 2",
         "P -6 c 2",
@@ -3894,7 +3894,7 @@ static HALL_SYMBOL_DATABASE: [HallSymbolEntry; 530] = [
     HallSymbolEntry::new(
         483,
         189,
-        56,
+        57,
         "",
         "P -6 -2",
         "P -6 2 m",
@@ -3904,7 +3904,7 @@ static HALL_SYMBOL_DATABASE: [HallSymbolEntry; 530] = [
     HallSymbolEntry::new(
         484,
         190,
-        56,
+        57,
         "",
         "P -6c -2c",
         "P -6 2 c",
@@ -4349,6 +4349,7 @@ static HALL_SYMBOL_DATABASE: [HallSymbolEntry; 530] = [
 #[cfg(test)]
 mod tests {
     use super::{HALL_SYMBOL_DATABASE, HallSymbolEntry};
+    use crate::data::arithmetic_crystal_class::arithmetic_crystal_class_entry;
     use crate::data::hall_symbol::HallSymbol;
 
     fn iter_hall_symbol_entry() -> impl Iterator<Item = &'static HallSymbolEntry> {
@@ -4362,4 +4363,26 @@ mod tests {
             assert_eq!(48 % hs.traverse().len(), 0);
         }
     }
+
+    #[test]
+    fn test_arithmetic_crystal_class_for_sg_187_to_190() {
+        // International Tables for Crystallography, Volume C (2004), Table 1.4.2.1
+        let expected = [
+            (187, 56, "-6m2P"),
+            (188, 56, "-6m2P"),
+            (189, 57, "-62mP"),
+            (190, 57, "-62mP"),
+        ];
+        for (number, arithmetic_number, symbol) in expected {
+            for entry in iter_hall_symbol_entry().filter(|entry| entry.number == number) {
+                assert_eq!(entry.arithmetic_number, arithmetic_number);
+                assert_eq!(
+                    arithmetic_crystal_class_entry(entry.arithmetic_number)
+                        .unwrap()
+                        .symbol,
+                    symbol
+                );
+            }
+        }
+    }
 }

moyo/src/data/point_group.rs

@@ -134,8 +134,8 @@ impl PointGroupRepresentative {
             53 => 469,
             54 => 471,
             55 => 477,
-            56 => 483,
-            57 => 481,
+            56 => 481,
+            57 => 483,
             58 => 485,
             // Cubic
             59 => 489,