Ju n 19 96 Submitted to Phys . Lett . B HUPS - 96 - 4 Four - Alpha Linear - Chain States in 16

We study 4α linear-chain states in 16 O in comparison with 3α states in 12 C by using the Generator Coordinate Method within a microscopic N α-cluster model. It is shown to be very important to solve relative motion of α-clusters by taking into account the orthogonality between the linear-chain states and other low-lying states including the ground state. For 12 C, the 3α chain state disappears because of this orthogonality. The 4α chain state in 16 O, on the other hand, is hardly affected by low-lying states and persists to remain above the 4α threshold. The calculated moment of inertia of the 4α linear-chain rotational band (88 keV) reproduces the experimentally suggested value qualitatively.