  With the time dependent Hartree-Fock (TDHF) theory, capture thresholds
$E_{\rm cap}$ for 144 fusion systems with nearly spherical nuclei are
systematically studied for the first time. We find that for the reactions
between doubly-magic nuclei, the calculated $E_{\rm cap}$ are very close to the
extracted barrier heights from measured fusion excitation functions. For the
fusion reactions with nearly spherical nuclei, an excitation energy of about 1
MeV at the capture position need to be considered to better reproduce the data
due to the lower excitation threshold. The rms deviation with respect to the
barrier heights is only 1.43 MeV from the TDHF calcualtions, which is smaller
than the results from three empirical nuclear potentials. Together with
Siwek-Wilczy\'{n}ski formula in which the three parameters are determined by
the TDHF calculations, the measured fusion cross sections at energies around
the barriers can be well reproduced for seven fusion reactions
$^{40}$Ca+$^{48}$Ca, $^{16}$O+$^{208}$Pb, $^{40}$Ca+$^{90,96}$Zr,
$^{28}$Si+$^{96}$Zr and $^{132}$Sn+$^{40,48}$Ca.
