Vibrational transition energies of trans-HCOOH with respect to the respective trans minimum reported as fundamentals in cm⁻¹ and computed with various ab initio methods and PES mentioned in this work as well as experimental values^{50,55,61,83,88,89,98} and RMSD with respect to the experimental values. The internal coordinate path Hamiltonian results are abbreviated with an I-prefix.

PES & method	ν 1	ν 2	ν 3	ν 4	ν 5	ν 6	ν 7	ν 8	ν 9	RMSD
200348	3784	3134	1789	1427	1317	1123	632	1065	677	98.7
Harm.48
200348	3551	2951	1757	1389	1268	1078	621	1035	598	23.5
CC-VSCF48
200720	3783	3106	1836	1429	1331	1144	634	1078	681	96.5
Harm.20
200720	3594	2949	1801	1402	1291	1114	628	1042	643	15.29
PT20
201335	3753	3081	1809	1414	1318	1137	629	1048	670	79.7
Harm.35
201335	3505	2915	1783	1376	1296	1123	636	1034	687	29.3
VSCF35
201335	3587	2944	1775	1365	1272	1102	624	1027	642	13.7
VMP235
201335	3542	2915	1783	1377	1321/1226	1124	629	1034	635	30.6
VASCI35
201335	3560	2923	1776	1364	1301/1203	1101	621	1027	625	36.0
VASPT235
201662	3767	3092	1818	1412	1323	1140	632	1056	673	86.3
Harm.62
201662	3551	2918	1790	1383	1305	1129	683	1040	648	28.2
I-VSCF62
201662	3553	2917	1790	1372	1289	1127	657	1042	633	3.4
I-VMP262
201662	3575	2939	1783	1379	1222	1108	627	1034	641	3.1
I-VCI62
201662	3576	2938	1783	1379	1304	1108	627	1034	639	3.8
GENIUSH30
201662	3576	2940	1783	1380	1305	1108	627	1035	640	2.8
CVPT679
201856	3823	3014	1845	1416	1288	1124	655	1036	520	100.6
Harm.56
201856	3567	2937	1774	1375	1301	1106	623	1032	637	3.6
MCTDH56
201856	3568	2939	1773	1374	1300	1106	623	1032	637	3.7
CVPT679
Exp.	3570.5	2942.06	1776.83	1379.05	1306.1	1104.85	626.17	1033.47	640.73