chematic-ff 0.6.0

//! MMFF94 Out-of-Plane and Stretch-Bend parameters (Halgren MMFF.V/VI).

/// MMFF94 Out-of-Plane parameters (117 entries, Halgren MMFF.VI)
/// Format: (type_i, type_j, type_k, type_l, koop)
/// type_i = central sp2 atom; j/k/l = three attached atoms (0=wildcard)
/// E_oop = (0.043844 × koop / 2) × χ² (χ in degrees, Halgren eq. 6)
pub static MMFF94_OOP: &[(u8, u8, u8, u8, f64)] = &[
    (0, 2, 0, 0, 0.0200),
    (0, 3, 0, 0, 0.1300),
    (0, 8, 0, 0, 0.0000),
    (0, 10, 0, 0, -0.0200),
    (0, 17, 0, 0, 0.0000),
    (0, 26, 0, 0, 0.0000),
    (0, 30, 0, 0, 0.0100),
    (0, 37, 0, 0, 0.0350),
    (0, 39, 0, 0, 0.0200),
    (0, 40, 0, 0, -0.0050),
    (0, 41, 0, 0, 0.1800),
    (0, 43, 0, 0, 0.0000),
    (0, 45, 0, 0, 0.1500),
    (0, 49, 0, 0, 0.0000),
    (0, 54, 0, 0, 0.0200),
    (0, 55, 0, 0, 0.0200),
    (0, 56, 0, 0, 0.0200),
    (0, 57, 0, 0, 0.0800),
    (0, 58, 0, 0, 0.0250),
    (0, 63, 0, 0, 0.0500),
    (0, 64, 0, 0, 0.0400),
    (0, 67, 0, 0, 0.0700),
    (0, 69, 0, 0, 0.0700),
    (0, 73, 0, 0, 0.0000),
    (0, 78, 0, 0, 0.0450),
    (0, 80, 0, 0, 0.0800),
    (0, 81, 0, 0, 0.0250),
    (0, 82, 0, 0, 0.0000),
    (1, 2, 1, 2, 0.0300),
    (1, 2, 2, 2, 0.0270),
    (1, 2, 2, 3, 0.0260),
    (1, 2, 2, 5, 0.0130),
    (1, 2, 2, 37, 0.0320),
    (1, 3, 1, 7, 0.1460),
    (1, 3, 2, 7, 0.1380),
    (1, 3, 3, 7, 0.1340),
    (1, 3, 5, 7, 0.1220),
    (1, 3, 6, 7, 0.1410),
    (1, 3, 7, 10, 0.1290),
    (1, 3, 7, 37, 0.1380),
    (1, 10, 1, 3, -0.0200),
    (1, 10, 3, 6, -0.0330),
    (1, 10, 3, 28, -0.0200),
    (1, 37, 37, 37, 0.0400),
    (1, 39, 63, 63, 0.0120),
    (1, 40, 28, 37, -0.0060),
    (1, 41, 32, 32, 0.1780),
    (1, 54, 3, 36, 0.0160),
    (1, 55, 36, 57, 0.0200),
    (1, 56, 36, 57, 0.0200),
    (2, 2, 2, 5, 0.0130),
    (2, 2, 3, 5, 0.0120),
    (2, 2, 5, 5, 0.0060),
    (2, 2, 5, 6, 0.0270),
    (2, 2, 5, 37, 0.0170),
    (2, 2, 5, 40, 0.0120),
    (2, 2, 5, 41, 0.0080),
    (2, 3, 5, 7, 0.1130),
    (2, 3, 5, 9, 0.0810),
    (2, 3, 6, 7, 0.1270),
    (2, 3, 7, 10, 0.1160),
    (2, 37, 37, 37, 0.0310),
    (2, 40, 28, 28, -0.0070),
    (2, 41, 32, 32, 0.1610),
    (3, 3, 5, 7, 0.1130),
    (3, 3, 6, 7, 0.1270),
    (3, 10, 3, 28, -0.0300),
    (3, 10, 28, 28, -0.0190),
    (3, 37, 37, 37, 0.0270),
    (3, 40, 28, 28, -0.0070),
    (3, 54, 36, 36, 0.0180),
    (5, 3, 5, 7, 0.1030),
    (5, 3, 5, 9, 0.0740),
    (5, 3, 5, 54, 0.0780),
    (5, 3, 6, 7, 0.1190),
    (5, 3, 7, 10, 0.1020),
    (5, 3, 9, 40, 0.0670),
    (5, 30, 20, 30, 0.0080),
    (5, 37, 37, 37, 0.0150),
    (5, 37, 37, 38, 0.0460),
    (5, 37, 37, 63, 0.0080),
    (5, 37, 37, 64, 0.0120),
    (5, 37, 37, 69, 0.0160),
    (5, 37, 38, 38, 0.0840),
    (5, 41, 32, 32, 0.1580),
    (5, 57, 55, 55, 0.0380),
    (5, 63, 39, 64, 0.0190),
    (5, 63, 39, 66, 0.0680),
    (5, 63, 44, 64, 0.0140),
    (5, 63, 44, 66, 0.0550),
    (5, 63, 59, 64, 0.0330),
    (5, 63, 59, 66, 0.0850),
    (5, 64, 63, 64, 0.0060),
    (5, 64, 63, 66, 0.0430),
    (5, 64, 64, 65, 0.0520),
    (5, 64, 65, 66, 0.0940),
    (5, 78, 78, 81, 0.0460),
    (5, 80, 81, 81, 0.0570),
    (6, 3, 7, 37, 0.1270),
    (6, 37, 37, 37, 0.0480),
    (7, 3, 10, 10, 0.1130),
    (7, 3, 20, 20, 0.1510),
    (9, 3, 40, 40, 0.0570),
    (15, 37, 37, 37, 0.0250),
    (23, 39, 63, 63, -0.0140),
    (23, 39, 63, 65, 0.0210),
    (23, 39, 65, 65, 0.0620),
    (28, 40, 28, 37, 0.0040),
    (32, 69, 37, 37, 0.0670),
    (36, 55, 36, 57, 0.0200),
    (36, 56, 36, 57, 0.0200),
    (36, 81, 78, 80, 0.0160),
    (37, 37, 37, 40, 0.0460),
    (37, 63, 39, 64, 0.0100),
    (37, 64, 63, 64, -0.0110),
    (50, 49, 50, 50, 0.0000),
    (56, 57, 56, 56, 0.1580),
];

/// MMFF94 Stretch-Bend parameters (282 entries, Halgren MMFF.V)
/// Format: (angle_type, type_i, type_j, type_k, kba_ijk, kba_kji)
/// E_sb = 2.51210 × (kba_ijk × Δr_ij + kba_kji × Δr_kj) × Δθ (degrees)
pub static MMFF94_STBN: &[(u8, u8, u8, u8, f64, f64)] = &[
    (0, 1, 1, 1, 0.2060, 0.2060),
    (0, 1, 1, 2, 0.1360, 0.1970),
    (0, 1, 1, 3, 0.2110, 0.0920),
    (0, 1, 1, 5, 0.2270, 0.0700),
    (0, 1, 1, 6, 0.1730, 0.4170),
    (0, 1, 1, 8, 0.1360, 0.2820),
    (0, 1, 1, 10, 0.1870, 0.3380),
    (0, 1, 1, 11, 0.2090, 0.6330),
    (0, 1, 1, 12, 0.1760, 0.3860),
    (0, 1, 1, 15, 0.1390, 0.2170),
    (0, 1, 1, 34, 0.2360, 0.4360),
    (0, 1, 1, 37, 0.1520, 0.2600),
    (0, 1, 1, 39, 0.1440, 0.5950),
    (0, 1, 1, 41, 0.1220, 0.0510),
    (0, 1, 1, 56, 0.2620, 0.4510),
    (0, 1, 1, 68, 0.1860, 0.1250),
    (0, 1, 2, 1, 0.2500, 0.2500),
    (0, 1, 2, 2, 0.2030, 0.2070),
    (0, 1, 2, 5, 0.2150, 0.1280),
    (0, 1, 3, 1, 0.3580, 0.3580),
    (0, 1, 3, 5, 0.3210, 0.1830),
    (0, 1, 3, 6, 0.3380, 0.7320),
    (0, 1, 3, 7, 0.1540, 0.8560),
    (0, 1, 3, 10, 0.2230, 0.7320),
    (0, 1, 6, 1, 0.3090, 0.3090),
    (0, 1, 6, 2, 0.1570, 0.3750),
    (0, 1, 6, 3, -0.1530, 0.2520),
    (0, 1, 6, 21, 0.2560, 0.1430),
    (0, 1, 6, 37, 0.1630, 0.3750),
    (0, 1, 8, 1, 0.3120, 0.3120),
    (0, 1, 8, 6, 0.2120, 0.3540),
    (0, 1, 8, 23, 0.3090, 0.1350),
    (0, 1, 9, 3, 0.3260, 0.5800),
    (0, 1, 10, 1, 0.0630, 0.0630),
    (0, 1, 10, 3, -0.0210, 0.3400),
    (0, 1, 10, 6, -0.0240, 0.3740),
    (0, 1, 10, 28, 0.1550, -0.0510),
    (0, 1, 15, 1, 0.1250, 0.1250),
    (0, 1, 15, 15, 0.0120, 0.2380),
    (0, 1, 15, 37, 0.0480, 0.2290),
    (0, 1, 15, 71, 0.0800, -0.0120),
    (0, 1, 18, 1, 0.0230, 0.0230),
    (0, 1, 18, 6, 0.0030, 0.2130),
    (0, 1, 18, 32, -0.0910, 0.3900),
    (0, 1, 18, 43, -0.0080, 0.6070),
    (0, 1, 20, 5, 0.2900, 0.0980),
    (0, 1, 20, 20, 0.1790, 0.0040),
    (0, 1, 22, 5, 0.0670, 0.1740),
    (0, 1, 22, 22, 0.1990, 0.0390),
    (0, 1, 34, 1, 0.2020, 0.2020),
    (0, 1, 34, 36, 0.1600, -0.0090),
    (0, 1, 37, 37, 0.4850, 0.3110),
    (0, 1, 39, 63, 0.3130, 0.5000),
    (0, 1, 40, 28, 0.2380, 0.0910),
    (0, 1, 40, 37, 0.1530, 0.5900),
    (0, 1, 41, 32, 0.5030, 0.9430),
    (0, 1, 54, 3, 0.1920, -0.0510),
    (0, 1, 54, 36, 0.2400, 0.0790),
    (0, 1, 55, 36, 0.1890, 0.0330),
    (0, 1, 55, 57, 0.1660, 0.2110),
    (0, 1, 56, 36, 0.2110, -0.0400),
    (0, 1, 56, 57, 0.0260, 0.3860),
    (0, 1, 68, 1, 0.2170, 0.2170),
    (0, 1, 68, 23, 0.2850, 0.0500),
    (0, 1, 68, 32, -0.0470, 0.5030),
    (0, 2, 1, 2, 0.2820, 0.2820),
    (0, 2, 1, 3, 0.2060, 0.0220),
    (0, 2, 1, 5, 0.2340, 0.0880),
    (0, 2, 1, 6, 0.1830, 0.3870),
    (0, 2, 1, 8, 0.2140, 0.3630),
    (0, 2, 2, 5, 0.2070, 0.1570),
    (0, 2, 2, 6, 0.1180, 0.5760),
    (0, 2, 2, 40, 0.2890, 0.3900),
    (0, 2, 2, 41, 0.1910, -0.0470),
    (0, 2, 6, 3, -0.2280, 0.0520),
    (0, 2, 6, 29, 0.2590, 0.1630),
    (0, 2, 40, 28, 0.3420, 0.1560),
    (0, 2, 41, 32, 0.5940, 0.9690),
    (0, 3, 1, 5, 0.1570, 0.1150),
    (0, 3, 1, 6, -0.0360, 0.4560),
    (0, 3, 1, 10, 0.0380, 0.1950),
    (0, 3, 6, 24, 0.2150, 0.0640),
    (0, 3, 6, 37, -0.2250, -0.3200),
    (0, 3, 9, 27, 0.4640, 0.2220),
    (0, 3, 10, 3, -0.2190, -0.2190),
    (0, 3, 10, 6, 0.4970, 0.5130),
    (0, 3, 10, 28, 0.1370, 0.0660),
    (0, 3, 20, 5, -0.0490, 0.1710),
    (0, 3, 40, 28, 0.2280, 0.1040),
    (0, 3, 54, 36, 0.0050, 0.1270),
    (0, 5, 1, 5, 0.1150, 0.1150),
    (0, 5, 1, 6, 0.0130, 0.4360),
    (0, 5, 1, 8, 0.0270, 0.3580),
    (0, 5, 1, 9, 0.0400, 0.4180),
    (0, 5, 1, 10, 0.0430, 0.2610),
    (0, 5, 1, 11, 0.0030, 0.4520),
    (0, 5, 1, 12, -0.0180, 0.3800),
    (0, 5, 1, 15, 0.0180, 0.2550),
    (0, 5, 1, 18, 0.1210, 0.2180),
    (0, 5, 1, 20, 0.0690, 0.3270),
    (0, 5, 1, 22, 0.0550, 0.2670),
    (0, 5, 1, 34, -0.0030, 0.3420),
    (0, 5, 1, 37, 0.0740, 0.2870),
    (0, 5, 1, 39, 0.0920, 0.6070),
    (0, 5, 1, 40, 0.0230, 0.3350),
    (0, 5, 1, 41, 0.0930, 0.1180),
    (0, 5, 1, 54, 0.0160, 0.3430),
    (0, 5, 1, 55, 0.0300, 0.3970),
    (0, 5, 1, 56, 0.0310, 0.3840),
    (0, 5, 1, 68, 0.0410, 0.2160),
    (0, 5, 2, 5, 0.1400, 0.1400),
    (0, 5, 2, 6, 0.2130, 0.5020),
    (0, 5, 2, 40, 0.0700, 0.4630),
    (0, 5, 2, 41, 0.1910, 0.0050),
    (0, 5, 3, 5, 0.1260, 0.1260),
    (0, 5, 3, 6, 0.1740, 0.7340),
    (0, 5, 3, 7, 0.0320, 0.8050),
    (0, 5, 3, 9, 0.0370, 0.6690),
    (0, 5, 3, 10, 0.1690, 0.6190),
    (0, 5, 3, 40, 0.0870, 0.6850),
    (0, 5, 3, 54, 0.0980, 0.2100),
    (0, 5, 20, 5, 0.1820, 0.1820),
    (0, 5, 20, 6, 0.0510, 0.3120),
    (0, 5, 20, 8, 0.0720, 0.2260),
    (0, 5, 20, 12, 0.0140, 0.5970),
    (0, 5, 20, 20, 0.1010, 0.0790),
    (0, 5, 20, 30, 0.1080, 0.1230),
    (0, 5, 22, 5, 0.2540, 0.2540),
    (0, 5, 22, 22, 0.1810, 0.1080),
    (0, 5, 26, 5, -0.1210, -0.1210),
    (0, 5, 30, 20, 0.2510, 0.0070),
    (0, 5, 30, 30, 0.2670, 0.0540),
    (0, 5, 37, 37, 0.2790, 0.2500),
    (0, 5, 37, 38, 0.2670, 0.3890),
    (0, 5, 37, 63, 0.2160, 0.4340),
    (0, 5, 37, 64, 0.1670, 0.3640),
    (0, 5, 37, 69, 0.2730, 0.3910),
    (0, 5, 41, 32, 0.2760, 0.8520),
    (0, 5, 57, 55, 0.0430, 0.4200),
    (0, 5, 63, 39, 0.0090, 0.6540),
    (0, 5, 63, 44, -0.0150, 0.4460),
    (0, 5, 63, 59, 0.0670, 0.5880),
    (0, 5, 63, 64, 0.0550, 0.3700),
    (0, 5, 63, 66, 0.1100, 0.4640),
    (0, 5, 64, 63, 0.0860, 0.3450),
    (0, 5, 64, 64, 0.0850, 0.3690),
    (0, 5, 64, 65, 0.0510, 0.4360),
    (0, 5, 64, 66, 0.1130, 0.4520),
    (0, 5, 78, 78, 0.2790, 0.2500),
    (0, 5, 78, 81, 0.0830, 0.2500),
    (0, 5, 80, 81, -0.1010, 0.6910),
    (0, 6, 1, 6, 0.3200, 0.3200),
    (0, 6, 1, 37, 0.3100, 0.1600),
    (0, 6, 3, 7, 0.4940, 0.5780),
    (0, 6, 8, 23, 0.4180, 0.0200),
    (0, 6, 18, 6, 0.0880, 0.0880),
    (0, 6, 18, 32, 0.1230, 0.3690),
    (0, 6, 37, 37, 0.8300, 0.3390),
    (0, 7, 3, 10, 0.7710, 0.3530),
    (0, 7, 3, 20, 0.8650, -0.1810),
    (0, 8, 6, 21, 0.3040, 0.0550),
    (0, 9, 3, 40, 0.6800, 0.2600),
    (0, 10, 3, 10, 1.0500, 1.0500),
    (0, 10, 6, 21, 0.4190, 0.1580),
    (0, 11, 1, 11, 0.5860, 0.5860),
    (0, 12, 1, 12, 0.5080, 0.5080),
    (0, 12, 20, 20, 0.3100, 0.0000),
    (0, 15, 15, 71, 0.1720, -0.0680),
    (0, 15, 37, 37, 0.6500, 0.2590),
    (0, 18, 6, 33, 0.3090, 0.1200),
    (0, 18, 43, 23, 0.3770, 0.0570),
    (0, 20, 8, 23, 0.1280, 0.1220),
    (0, 23, 8, 23, 0.1900, 0.1900),
    (0, 23, 39, 63, -0.1310, 0.4220),
    (0, 23, 39, 65, -0.1220, 0.2810),
    (0, 23, 43, 23, 0.0820, 0.0820),
    (0, 23, 68, 23, 0.1450, 0.1450),
    (0, 23, 68, 32, -0.1820, 0.5040),
    (0, 28, 10, 28, 0.0810, 0.0810),
    (0, 28, 40, 28, 0.0940, 0.0940),
    (0, 28, 40, 37, 0.1860, 0.4230),
    (0, 29, 6, 37, 0.1300, 0.2410),
    (0, 31, 6, 31, 0.2270, 0.2270),
    (0, 31, 70, 31, 0.2100, 0.2100),
    (0, 32, 18, 32, 0.4040, 0.4040),
    (0, 32, 18, 43, 0.3840, 0.2810),
    (0, 32, 41, 32, 0.6520, 0.6520),
    (0, 32, 69, 37, 1.0180, 0.4180),
    (0, 36, 34, 36, 0.0870, 0.0870),
    (0, 36, 54, 36, 0.1480, 0.1480),
    (0, 36, 55, 36, 0.1060, 0.1060),
    (0, 36, 55, 57, 0.0930, 0.0800),
    (0, 36, 56, 36, 0.1010, 0.1010),
    (0, 36, 56, 57, 0.1080, 0.0680),
    (0, 36, 81, 78, 0.0210, 0.3680),
    (0, 36, 81, 80, 0.0180, 0.4220),
    (0, 37, 15, 71, 0.1870, -0.0270),
    (0, 37, 37, 37, -0.4110, -0.4110),
    (0, 37, 37, 38, -0.4240, -0.4660),
    (0, 37, 37, 40, 0.4290, 0.9010),
    (0, 37, 37, 63, -0.1730, -0.2150),
    (0, 37, 37, 64, -0.2290, -0.2290),
    (0, 37, 37, 69, -0.2440, -0.5550),
    (0, 37, 38, 37, -0.3420, -0.3420),
    (0, 37, 38, 38, -0.1640, -1.1300),
    (0, 37, 63, 39, 0.1780, 0.5230),
    (0, 37, 63, 64, -0.0450, 0.4970),
    (0, 37, 64, 63, 0.0590, 0.2990),
    (0, 37, 64, 64, 0.2770, 0.3770),
    (0, 37, 69, 37, -0.1690, -0.1690),
    (0, 38, 37, 38, -0.5160, -0.5160),
    (0, 39, 63, 64, 0.4220, 0.4090),
    (0, 39, 63, 66, 0.4360, 0.5250),
    (0, 39, 65, 64, 0.5280, 0.6440),
    (0, 39, 65, 66, 0.3970, 0.2580),
    (0, 40, 3, 40, 0.4820, 0.4820),
    (0, 43, 18, 43, 0.4280, 0.4280),
    (0, 44, 63, 64, 0.5810, 0.4260),
    (0, 44, 63, 66, 0.5420, 0.3650),
    (0, 44, 65, 64, 0.8160, 0.5430),
    (0, 50, 49, 50, 0.0720, 0.0720),
    (0, 55, 57, 55, 0.1250, 0.1250),
    (0, 56, 57, 56, 0.4310, 0.4310),
    (0, 58, 57, 58, 0.7320, 0.7320),
    (0, 59, 63, 64, 0.8520, 0.3320),
    (0, 59, 63, 66, 0.7750, 0.3000),
    (0, 59, 65, 64, 1.1770, 0.5940),
    (0, 63, 39, 63, 0.4690, 0.4690),
    (0, 63, 39, 65, 0.7410, 0.5060),
    (0, 63, 44, 63, 0.5910, 0.5910),
    (0, 63, 44, 65, 0.8570, 0.9780),
    (0, 63, 59, 63, 0.4970, 0.4970),
    (0, 63, 59, 65, 0.7230, 0.8740),
    (0, 63, 64, 64, 0.2060, 0.0300),
    (0, 63, 64, 66, 0.1710, 0.0780),
    (0, 63, 66, 64, 0.2130, -0.1730),
    (0, 63, 66, 66, 0.2340, 0.0770),
    (0, 64, 64, 65, 0.0790, 0.4030),
    (0, 64, 66, 65, -0.1490, 0.3830),
    (0, 65, 39, 65, 0.7060, 0.7060),
    (0, 65, 64, 66, 0.4060, 0.0660),
    (0, 65, 66, 66, 0.1990, 0.1010),
    (0, 71, 15, 71, 0.0450, 0.0450),
    (0, 78, 78, 81, -0.3980, 0.3140),
    (0, 78, 81, 80, 0.3660, 0.4190),
    (0, 81, 80, 81, 0.7320, 0.7320),
    (1, 2, 2, 2, 0.2500, 0.2190),
    (1, 2, 2, 5, 0.2670, 0.1590),
    (1, 2, 3, 5, 0.4070, 0.1590),
    (1, 2, 3, 6, 0.4290, 0.4730),
    (1, 2, 3, 7, 0.2140, 0.7940),
    (1, 2, 3, 9, 0.2270, 0.6100),
    (1, 2, 3, 10, 0.2980, 0.6000),
    (1, 2, 37, 37, 0.3210, 0.2350),
    (1, 3, 2, 5, 0.2640, 0.1560),
    (1, 3, 3, 5, 0.2510, 0.1330),
    (1, 3, 3, 6, 0.0660, 0.6680),
    (1, 3, 3, 7, -0.0930, 0.8660),
    (1, 3, 37, 37, 0.1790, 0.2170),
    (2, 1, 2, 2, 0.2220, 0.2690),
    (2, 1, 2, 3, 0.2440, 0.2920),
    (2, 1, 2, 37, 0.2460, 0.2600),
    (2, 1, 3, 2, 0.2460, 0.4090),
    (2, 1, 3, 3, 0.3030, 0.1450),
    (2, 1, 3, 37, 0.2170, 0.2070),
    (2, 2, 2, 3, 0.1550, 0.1120),
    (2, 2, 2, 37, 0.1430, 0.1720),
    (2, 5, 2, 37, 0.1530, 0.2880),
    (2, 6, 3, 37, 0.3500, 0.1750),
    (2, 7, 3, 37, 0.7070, 0.0070),
    (4, 3, 6, 20, 0.4560, 0.3790),
    (4, 3, 20, 20, 0.6070, 0.4370),
    (4, 6, 3, 20, 1.1790, 0.7520),
    (4, 6, 20, 20, 0.8230, 0.3960),
    (4, 8, 20, 20, 0.7010, 0.3690),
    (4, 20, 3, 20, 0.5360, 0.5360),
    (4, 20, 6, 20, 0.7390, 0.7390),
    (4, 20, 8, 20, 0.6530, 0.6530),
    (4, 20, 20, 20, 0.2830, 0.2830),
    (4, 20, 20, 30, 0.3400, 0.5290),
    (4, 20, 30, 30, 0.4130, 0.7050),
    (5, 22, 22, 22, 0.0000, 0.0000),
];

/// Look up OOP bending parameter for central sp2 atom j with neighbors i, k, l.
/// Wildcard matching (0) tried as fallback.
pub fn mmff94_oop(type_j: u8, type_i: u8, type_k: u8, type_l: u8) -> Option<f64> {
    // Normalize: sort (i, k, l) except j stays central; try all orderings via wildcard
    for &(ti, tk, tl) in &[
        (type_i, type_k, type_l),
        (type_k, type_i, type_l),
        (type_l, type_k, type_i),
        (type_i, type_l, type_k),
        (type_k, type_l, type_i),
        (type_l, type_i, type_k),
    ] {
        if let Some(koop) = search_oop(type_j, ti, tk, tl) {
            return Some(koop);
        }
    }
    // Wildcard fallback
    for &(ti, tk, tl) in &[(0, 0, 0), (type_i, 0, 0), (0, type_k, 0), (0, 0, type_l)] {
        if let Some(koop) = search_oop(type_j, ti, tk, tl) {
            return Some(koop);
        }
    }
    None
}

fn search_oop(type_j: u8, type_i: u8, type_k: u8, type_l: u8) -> Option<f64> {
    MMFF94_OOP
        .binary_search_by_key(&(type_i, type_j, type_k, type_l), |&(i, j, k, l, _)| {
            (i, j, k, l)
        })
        .ok()
        .map(|idx| MMFF94_OOP[idx].4)
}

/// Look up Stretch-Bend parameters for angle i-j-k.
/// Returns (kba_ijk, kba_kji). Both orderings (i,j,k) and (k,j,i) tried.
pub fn mmff94_stbn(angle_type: u8, type_i: u8, type_j: u8, type_k: u8) -> Option<(f64, f64)> {
    let search = |at: u8, ti: u8, tj: u8, tk: u8| {
        MMFF94_STBN
            .binary_search_by_key(&(at, ti, tj, tk), |&(a, i, j, k, _, _)| (a, i, j, k))
            .ok()
            .map(|idx| (MMFF94_STBN[idx].4, MMFF94_STBN[idx].5))
    };
    search(angle_type, type_i, type_j, type_k)
        .or_else(|| search(angle_type, type_k, type_j, type_i).map(|(a, b)| (b, a)))
        .or_else(|| search(0, 0, type_j, 0))
}