“…[12,13] (see Section 2.2). b Instead of these torsional modes, the contributions due to the internal rotation were calculated using the following coefficients V n in equation (6), reduced moment of inertia I r and symmetry number of rotor r m : CH 3 group: I r = 0.5230 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 1169 cm À1 , CH 3 group: I r = 0.5222 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 1103 cm À1 , CH 3 group: I r = 0.5217 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 1122 cm À1 , CH 3 group: I r = 0.5230 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 1121 cm À1 , CH 3 group: I r = 0.5174 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 1042 cm À1 , t-C 4 H 9 group: I r = 7.6485 AE 10 À39 g AE cm 2 , r m = 3, V 3 = 980 cm À1 , i-C 4 H 9 group: I r = 7.3771 AE 10 À39 g AE cm 2 , r m = 1, V 1 = 3973.1, V 2 = À1564.5, V 3 = 726.1, V 4 = À173.0, V 5 = 120.0, V 6 = 7.2 (in cm À1 ), i-C 3 H 7 group: I r = 7.4922 AE 10 À39 g AE cm À1 , r m = 1, V 1 = À438.1, V 2 = 230.8, V 3 = 1680.2, V 4 = 74.4, V 5 = 25.2, V 6 = À79.7 (in cm À1 ).…”