  Structures of $p$- and $sd$-shell nuclei are studied with the deformed-basis
antisymmetrized molecular dynamics method using the Gogny D1S and Skyrme SLy7
forces as effective interactions. By the energy variation with a constraint,
energy curves as functions of quadrupole deformation parameter $\beta$ are
obtained. The energy curves for $sd$-shell nuclei show structure change as a
function of $\beta$, and suggest shape coexistence. Nuclear structures in the
deformed region are discussed focusing on deformations and clustering. It is
found that the deformations often involve cluster structures.
Effective-interaction dependence is also discussed comparing the results
obtained with the two effective interactions. Although the two forces give
similar results when cluster structures do not develop clearly, they give
different energies in the largely deformed region when an $\alpha$ cluster
develops.
