Among the tested force fields, CHARMM36 with ECC charge scaling with a 0.85 scaling factor and the standard AMBER99SB full charges perform the best, in line with the fact that charge scaling tends not to be a decisive factor for the pairing of a low charge density ions like TMA. The two force fields give a very similar picture of weak ion pairing with the acetate lying flat against the TMA surface. However, none of the investigated force fields captures all the features of the experimental signal, in particular, the intensity of the peak at low Q in reciprocal space. In contrast, AIMD simulations based on the revPBE DFT functional provide an excellent fit to experiment, properly capturing also this feature.