Actually, the first quantum chemical calculation of a chemical system by Heitler and London in 1927 was based on this theory. In a typical valence-bond calculation, the input consists of strictly ...

Lu Qiu, Xiuyun Zhang, Xiao Kong, Izaac Mitchell, Tianying Yan, Sung Youb Kim, Boris I. Yakobson, and Feng Ding, “Theory of sigma bond resonance in flat boron materials” Nature Communications ...