Calculated vibrational frequencies of L-Valine S. No Symmetry Species Cs Observed Frequency(cm-1) FTIR    FTRaman Methods Vibrational  Assignments HF B3LYP B3PW91 6-311+G (d, p) 6-31+G (d, p) 6-311+G (d, p) 6-31+G (d, p) 6-311+G (d, p) 1 A′ 3550w - 3662 3551 3550 3547 3551 (O-H)  υ 2 A′ 3460s 3460m 3458 3455 3462 3472 3470 (N-H)  υ 3 A′ 3350s 3350m 3373 3351 3347 3348 3340 (N-H)  υ 4 A′ 2970s 2970vs 2976 2986 2967 2965 2970 (C-H) υ 5 A′ 2930vs - 2922 2934 2918 2917 2941 (C-H) υ 6 A′ 2920vs 2920s 2911 2922 2906 2906 2936 (C-H) υ 7 A′ - 2910vs 2900 2915 2898 2900 2925 (C-H) υ 8 A′ 2890s 2890s 2868 2863 2903 2840 2877 (C-H) υ 9 A′ 2880s - 2855 2856 2895 2834 2871 (C-H) υ 10 A′ 2860s - 2851 2854 2851 2832 2862 (C-H) υ 11 A′ 2850s - 2846 2841 2837 2820 2844 (C-H) υ 12 A′ 1710m - 1834 1732 1727 1731 1727 (C=O) υ 13 A′ 1620vs 1620w 1629 1618 1619 1620 1620 (O-H) δ 14 A′ - 1495s 1483 1486 1483 1494 1503 (N-H) δ 15 A′ 1465vs - 1466 1468 1467 1466 1470 (N-H) δ 16 A′ - 1460s 1462 1460 1459 1457 1456 (CH3) α 17 A′ - 1450vs 1452 1452 1451 1449 1446 (CH3)α 18 A′ 1400vs - 1401 1405 1405 1404 1395 (CH3) α 19 A′ 1395vs - 1397 1388 1394 1394 1393 (CH3) α 20 A″ 1375vs - 1380 1368 1383 1374 1374 (O-H) γ 21 A′ 1370vs - 1371 1366 1372 1361 1373 (C-N)  υ 22 A′ 1350vs 1350m 1352 1348 1353 1343 1347 (C-H)  δ 23 A′ 1325s - 1314 1337 1320 1334 1323 (C-H)  δ 24 A′ 1270s 1270w 1267 1277 1262 1272 1279 (C-O)  υ 25 A′ 1190m - 1190 1188 1191 1197 1181 (C-H)  δ 26 A′ - 1170m 1179 1171 1180 1180 1171 (C-H)  δ 27 A′ 1165m - 1163 1165 1167 1164 1161 (C-H)  δ 28 A′ 1140m 1140m 1126 1145 1130 1133 1141 (C-H)  δ 29 A′ 1105vw - 1092 1106 1105 1115 1115 (C-H)  δ 30 A′ - 1050vs 1041 1044 1047 1052 1054 (C-C)  υ 31 A′ 940m 940s 931 945 939 932 930 (C-C-N) υ 32 A′ - 935s 937 940 953 943 933 C-(CH3) υ 33 A″ 900w - 908 911 899 924 902 (C-C)  υ (N-H) γ 34 A″ - 870vs 885 864 869 868 869 (N-H) γ 35 A″ 850w - 842 838 840 846 852 (C-H) γ 36 A″ - 820m 811 792 805 832 828 (C-H) γ 37 A″ 720s - 727 774 776 773 767 (C-H) γ 38 A″ 710s   697 705 720 713 708 (C-H) γ 39 A″ 560s 560w 589 564 552 567 628 (C-H) γ 40 A″ - 500w 512 541 518 542 511 (C-H) γ 41 A″ 450m - 450 450 431 449 443 (C-H) γ 42 A″ - 390w 395 384 386 383 387 (C-C) δ (C-H) γ 43 A′ - 360w 365 360 361 364 363 (C-C) δ 44 A″ - 340w 339 341 340 332 337 (CO2) γ 45 A′ - 310w 325 329 324 325 316 C-(CH3)  δ 46 A″ - 280w 278 273 273 286 269 (C-C)  γ (C-N) γ 47 A″ - 220w 249 234 234 232 221 C-(CH3) γ 48 A″ - 210w 209 216 215 215 199 (CH3) τ 49 A″ - 200w 195 202 191 202 185 (CH3) τ 50 A″ - 150w 74 78 70 79 74 (NH2)  τ 51 A″ - 140w 60 41 41 41 39 (C=O-OH) τ VS –Very strong; S – Strong; m- Medium; w – weak; as - Asymmetric; s – symmetric; υ – stretching; α –deformation, δ - In plane bending; γ - out plane bending; τ – Twisting

Table 2: Observed and HF and DFT (B3LYP & B3PW91) with 6-31+G(d,p) & 6-311+G (d,p) level.