The potential energy surfaces of the neutral and anionic thymine-water complexes are
investigated using high level ab initio calculations. Both dipole bound (DB) and valence
bound (VB) anionic forms are considered. Four minima and three rst order stationary
points are located, and binding energies are computed. All minima, for both anions, are
found to be vertically and adiabatically stable. Binding energies are much higher for valence
bound than for dipole bound anions. Adiabatic electron anities are in the 66-287 meV
range for VB anions and 4-60 meV range for DB anions, and vertical detachment energies
are in the 698-977 meV and 10-70 meV range for VB and DB anions, respectively. For
cases where literature data are available, the computed values are in good agreement with
previous experimental and theoretical studies. It is observed that electron attachment,
especially for the valence bound anions, reduces the size of the energy barrier between
adjacent minima, rendering the coexistence of dierent structures more probable.