The good performance of CNEO-MD in H 5 O + 2 and H 3 O - 2 demonstrates its great potential as an accurate and efficient method for proton transfer studies, especially in large systems where MCTDH and VSCF/VCI calculations are too expensive to perform. Here we extend our method to another important category of shared proton systems, proton-bound organic molecules/ions, and use the proton-bound formate dimer (AHA -) as an example to study. The AHA -system was previously studied by cold-ion IR action spectroscopy and discrete variable representation (DVR) analysis, both of which revealed that the bridging proton Figure : IR spectra of H 3 O - 2 by conventional AIMD and CNEO-MD at 10 K. Experimental IR spectrum is from Ref. . is shared equally between two formate anions. It was also found that the fundamental of the proton transfer mode ν ∥ is strongly coupled to the out-of-phase carboxylate deformation mode, δ(OCO) OOP . Similar to the H 5 O + 2 and H 3 O - 2 cases, we perform both static calculations and molecular dynamics simulations to the AHA -system.