  A chiral 4-fermion or 4-unit charge Coulomb structure for perturbed atom H
implies that an intra-atomic H-Hbar transition must obey the same quantitative
criteria as a classical intra-molecular Walden inversion. In a trigonal pyramid
model for chiral molecule ABCD with A at the top, chirality is minimal when A
crosses mirror plane BCD at critical angle pi/2 radians or 90 degrees. This
angle is reproduced with one-electron energies of natural perturbed atom H. We
prove how these results are still consistent with Bohr theory and the observed
H-spectrum. Unlike bound state QED, we promote hydrogen mass to a critical
variable and obtain, from first principles, a critical n-value equal to pi. We
detect a Mexican hat or double well potential, hidden in the observed terms of
natural perturbed atom H, which reveals how the symmetry of the electron-proton
bond is broken naturally. The result is that recent claims by ATHENA- and
ATRAP-collaborations on the mass production of Hbar may well be premature and
that H-Hbar bonding schemes may have to be reconsidered, in line with recent
observations (note added in proof: G. Van Hooydonk, Eur Phys J D, 32, 299
(2005)).
