#P HF/6-31G(d) opt=Z-Matrix

H2 + H rad substitution ts, HF/6-31G(d)
pushing r3

0 2
H1
X2  1  1.0
H3  1  r3  2  90.0
H4  1  r4  2  90.0  3  180.0

r3=0.729971 S 20 +0.1
r4=3.491454