  The Semimicroscopic Algebraic Cluster Model (SACM) is applied to 16O, assumed
to consist of a system of four alpha-clusters. For the 4-alpha cluster system a
microscopic model space is constructed, which observes the
Pauli-Exclusion-Principle (PEP) and is symmetric under permutation of the
4-alpha-particles. A phenomenological Hamiltonian is used, justifying the name
Semi in the SACM. The spectrum and transition values are determined. One of the
main objectives is to test the importance of the Pauli Exclusion Principle
(PEP), comparing the results with the Algebraic Cluster Model (ACM), which does
not include the PEP, and claims that the 16O shows evidence of a tetrahedral
structure, which can be explained easily by symmetry arguments. We show that
PEP is very important and cannot be neglected, otherwise it leads to a wrong
interpretation of the band structure and to too many states at low energy.
