Angular-momentum projection in coupled-cluster theory: Structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Mg</mml:mi><mml:mprescripts /><mml:none /><mml:mn>34</mml:mn></mml:mmultiscripts></mml:math>

Single-reference coupled-cluster theory is an accurate and affordable computational method for the nuclear many-body problem. For open-shell nuclei, reference state typically breaks rotational invariance angular momentum must be restored as a good quantum number. We perform angular-momentum projection after variation employ disentangled formalism Hermitian approach. compare our results with benchmarks $^8$Be $^{20}$Ne using two-nucleon interaction from chiral effective field $pf$-shell nuclei within traditional shell model. compute band in exotic nucleus $^{34}$Mg find agreement data.