Triaxial deformation in 10Be -: art. no. 044302

The triaxial deformation in Be-10 is investigated using a microscopic alpha+alpha+n+n model. The states of two valence neutrons are classified based on the molecular-orbit (MO) model, and the pi orbit is introduced about the axis connecting the two alpha clusters for the description of the rotational bands. There appear two rotational bands comprised mainly of K-pi=0(+) and K-pi=2(+), respectively, at low excitation energy, where the two valence neutrons occupy K-pi=3/2(-) or K-pi=1/2(-) orbits. The triaxiality and the K mixing are discussed in connection to the molecular structure, particularly to the spin-orbit splitting. The extent of the triaxial deformation is evaluated in terms of the electromagnetic transition matrix elements (Davydov-Filippov model, Q-invariant model) and density distribution in the intrinsic frame. The obtained values turned out to be gamma=15degrees-20degrees.