  Background: Recent accumulation of experimental data is revealing the nuclear
deformation in vicinity of 42Si. This requests systematic theoretical studies
to clarify more specific aspects of nuclear deformation and its causes.
Purpose: The purpose of this study is to investigate the nature and cause of
the nuclear deformations and its relation to the loss of the neutron magic
number N = 28 in vicinity of 42Si. Method: The framework of antisymmetrized
molecular dynamics with Gogny D1S density functional has been applied. The
model assumes no spatial symmetry and can describe triaxial deformation. It
also incorporates with the configuration mixing by the generator coordinate
method. Results: We show that the shell effects and the loss of the magicity
induce various nuclear deformations. In particular, the N = 26 and N = 30
isotones have triaxially deformed ground states. We also note that the erosion
of the N = 28 magicity gradually occurs and has no definite boundaries.
Conclusion: The present calculation predicts various nuclear deformations in
vicinity of 42Si and suggests that the inter-band electric transitions are good
measure for it. We also remark that the magicity is lost without the
single-particle level inversion in the oblate deformed nuclei such as 42Si.
