S.No Symmetry Species CS Observed Frequency (cm-1) FTIR    FTRaman Methods Vibrational  Assignments HF B3LYP B3PW91   6-31+G (d, p) 6-311+G (d, p) 6-31+G (d, p) 6-311+G (d, p) 1 A’ 3300w - 3295 3255 3327 3336 3292 (O-H)  υ 2 A’ 2960vs - 2995 2959 2979 2957 2950 (C-H)  υ 3 A’ 2950vs - 2988 2955 2975 2954 2946 (C-H)  υ 4 A’ - 1640vs 1649 1665 1648 1648 1633 (C=C) υ 5 A’ - 1630vs 1634 1638 1619 1629 1610 (C=C)  υ 6 A’ 1620vs - 1616 1622 1632 1617 1597 (C=C)  υ 7 A’ 1550vs - 1552 1555 1548 1575 1564 (N-O) υ as 8 A’ 1540vs - 1540 1539 1531 1561 1551 (N-O) υ as 9 A’ - 1475s 1460 1455 1468 1474 1459 (N-O) υ as 10 A’ 1450vs - 1449 1452 1432 1426 1455 (C-C) υ 11 A’ - 1445vs 1447 1435 1448 1452 1440 (C-C) υ 12 A’ - 1440vs 1441 1427 1411 1455 1440 (C-C) υ 13 A’ 1420vs - 1420 1416 1398 1443 1429 (N-O) υs 14 A’ 1340w 1340vs 1324 1336 1351 1317 1344 (N-O) υs 15 A’ 1310vs - 1311 1309 1319 1292 1314 (N-O) υs 16 A’ 1250vs - 1206 1258 1250 1266 1290 (O-H) δ 17 A’ 1180m - 1185 1175 1187 1157 1180 (C-H)  δ 18 A’ - 1150vs 1168 1154 1145 1119 1150 (C-H)  δ 19 A’ 1090vs   1094 1994 1091 1091 1090 (C-N)  υ 20 A’ 1085vs 1085vs 1048 997 995 993 991 (C-N)  υ 21 A’ 950m - 991 947 960 923 945 (C-N)  υ 22 A’ - 940m 959 937 950 919 938 (C-O)  υ 23 A" - 920vs 941 914 931 903 928 (C-H)  γ 24 A" 835m - 851 840 849 816 845 (C-H)  γ 25 A" 830m 830m 828 837 840 809 830 (O-H)  γ 26 A’ - 800vs 806 793 809 803 818 (NO2)  δ 27 A’ - 795s 785 798 797 807 791 (NO2)  δ    28 A’ 780vs - 768 160 760 782 770 (NO2)  δ  29 A’ 740vs 740s 735 757 744 766 737 (CCC)  δ 30 A’ 730vs 730vs 725 756 728 761 726 (CCC)  δ 31 A’ 700vs 700vs 704 733 703 738 714 (CCC)  δ 32 A’ - 660w 661 719 688 723 646 (C-N)  δ 33 A’ 650w - 647 670 647 673 650 (C-N)  δ 34 A’ 550w 550w 541 560 548 561 550 (C-N)  δ 35 A" - 530w 525 858 533 516 533 (NO2) γ 36 A" 510w - 506 515 511 508 514 (NO2) γ 37 A" 420m - 435 461 410 433 408 (NO2) γ 38 A" 400m 400m 396 412 402 388 403 (CCC)  γ 39 A" 360w - 372 390 349 365 363 (CCC)  γ 40 A" 340m 340w 344 355 338 333 342 (CCC)  γ 41 A’ 330w - 336 351 332 329 336 (C-O)  δ 42 A" 320m - 322 333 321 312 323 (C-N)  γ 43 A" 310m 310w 310 324 310 303 311 (C-N)  γ 44 A" 200m 200m 198 207 198 195 199 (C-N)  γ   45 A" 190w - 183 192 188 192 188 (C-O) γ 46 A" 150w 150m 154 158 150 148 153 (C-N) γ   47 A" 120w - 124 131 121 131 125 (C-N) γ 48 A" 110w - 88 101 97 102 96 (C-OH) τ 49 A" 105w - 53 62 60 62 60 (NO2) τ 50 A" 100w 100w 52 57 53 57 52 (NO2) τ 51 A" 90w - 49 46 51 46 51 (NO2)τ

VS – Very –Strong; S – Strong; m- Medium; w – weak; as- Asymmetric; s – symmetric; υ – stretching; δ- In plane bending; γ– out plane bending; τ – Twisting:

Table 2: Observed and HF/DFT (LSDA & B3LYP) with 6-31& 6-311G (d, p) level calculated vibrational frequencies of 2,4,6-Nitrophenol.