晶体表面吸附氢，能量、结构计算问题

hopedream

有两点需要请教：
1. 图中的H2标定了能量为0，不懂啊
2.TS1这个应该是过渡态，文章没有详细描述，我判断的。但是过渡态如何获得结构，如何计算吸附能呢？

以下是文章对这个图的描述：
Following Pathway I, two major reaction steps，namely,
hydrogen activation and hydrogen transfer，are involved. In
the hydrogen activation step, first, the H2 molecule is weakly
adsorbed on the catalyst (Figure 2,IM1), with the adsorption
energy of −0.14 eV and the shortest distance between the
physisorbed H2 and B-doped phosphorene of 3.30 Å. The
physisorbed H2 molecule then dissociates heterolytically into
two separated H atoms，one atom (Ha) bound to B site and
the other (Hb) bound to P site, thus generating hydridic (Ha)
and protic (Hb) hydrogens. Note that there are three
nonequivalent B/P pairs in B-doped phosphorene, namely,
(i) B/P2, (ii) B/P4, and (iii) B/P5 sites, to accommodate the
two dissociated H atoms.