Through the optimization of sphere radii ratios, seven tetrahedral hydrides species withequal valence electrons are investigated by means of SCF-X_αSW method in muffin-tin ap-proximation scheme. In comparison with those published results, the calculated total statis-tical energies and the corresponding binding energies of neutral molecules concerned have beenmuch better improved, which offers reasonable interpretation of their bonding stabilities, no-tably for SiH_4 and GeH_4. For ionic species, attention is focused on the role of Watson sphere,thus two kinds of calculation with and withcut Watson sphere are simultaneously given for com-parison. It reveals that free ions always behave more unstably and Watson sphere seems tobe a suitable model for describing the environment of a stabilized ion. The calculated bind-ing energies of ions have been utilized to correlate the thermostability trend for a few crystalcompounds. Also, an empirical linear relationship between optimized sphere radii ratios andelee Through the optimization of sphere radii ratios, seven tetrahedral hydrides species withequal valence electrons are investigated by means of SCF-X_αSW method in muffin-tin ap-proximation scheme. Among these published total statis-tical energies and the corresponding binding energies of neutral molecules concerned have been better improved, which offers reasonable interpretation of their bonding capabilities, no-tably for SiH_4 and GeH_4. For ionic species, attention is focused on the role of Watson sphere, thus two kinds of calculation with and withcut Watson sphere are successively given for com-parison. It reveals that free ions always behave more unstably and Watson sphere seems tobe a suitable model for describing the environment of a stabilized ion. The calculated bind-ing energies of ions have been utilized to correlate the thermostability trend for a few crystalcompounds. Also, an empirical linear relationship between optimized sphere ra dii ratios andelee