Formic acid (FA), HCOOH, is the simplest carboxylic acid. Its two oxygen acceptor sites and two hydrogen bond acceptor sites provide several possibilities for hydrogen bond formation. Thus, it can be regarded as an archetypal molecule for the study of important fundamental phenomena such as hydrogen bond geometry and strength, proton transfer, and polymerization. Based on our ab initio CASTEP predictions for INS and NCS spectra, we propose to test the hypothesis by Zelsmann et al. of the coexistence of the beta1 and beta2 phases above 220 K. NCS spectra will be recorded at T = 10, 200, and 240 K. The widths of NMDs of H, C, O obtained from the experiments will be compared with the results of our ab initio prediction for the beta1 phase. In particular, the degree anisotropy of the measured NMDs will be characterised in terms of the Gram-Charlier expansion (GC) fits to NCS data.