The three-dimensional Thomas-Fermi (TF) model is used to simulate the
variation of the d+d to t + p cross-section at low impact energies, when the
target deuterium nucleus is embedded in metallic or insulator environments.
Comparison of the computational results to recent experiments demonstrates that
even though the TF model can explain some increase in the low energy cross
section for metallic host, a full explanation of the experimental results is
still lacking. Possible reasons for the disagreement are discussed.Comment: 6 pages;6 figures. Accepted for publication in Eur. Phys. Jour.