All three systems have an electron donating amino group at position 2 and an electron withdrawing group which allow for a hydrogen bond to the amino group in position 1. The three high energy density systems have very low back reaction barriers making them unsuitable for storage purposes. The amino group in position 2 have been shown to yield a large increase in storage energy, but also results in a significant decrease of the back reaction barrier . The hydrogen bond between the amino group and the electron withdrawing group stabilizes the DHA system increasing the storage energy, also locks VHF in the s-cis-VHF conformer. This means that the most stable VHF conformer is structurally Figure : (a) Electronic barrier heights and storage energies computed for 32,623 singlyand doubly substituted molecules using SQM and "5 + 5n rot " conformations as described in the Computational Methodology section. (b) Electronic barrier heights and storage energies computed for the 109 molecules in the green box in (a) computed using M06-2X/6-31G(d). The geometry optimizations are started from the SQM structures and the purple box highlights 10 molecules selected for further study (Table ). The vertical and horizontal lines mark the storage energy and barrier height for the parent molecule illustrated in Figure .