Small clusters of formic acid: Tests and applications of density functional theory with dispersion-correcting potentials

► B3LYP-DCP method does not give spurious effects in formic acid trimers. ► B3LYP-DCP works quite well for π-stacking formic acid tetramers. ► Improved predictions for formic acid pentamer structures. ► Planar structures are unimportant for formic acid pentamers.