  Azimuthal correlations between the two jets with the largest transverse
momenta $ {p_{\mathrm{T}}} $ in inclusive 2-, 3-, and 4-jet events are
presented for several regions of the leading jet $ {p_{\mathrm{T}}} $ up to 4
TeV. For 3- and 4-jet scenarios, measurements of the minimum azimuthal angles
between any two of the three or four leading $ {p_{\mathrm{T}}} $ jets are also
presented. The analysis is based on data from proton-proton collisions
collected by the CMS Collaboration at a centre-of-mass energy of 13 TeV,
corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Calculations based
on leading-order matrix elements supplemented with parton showering and
hadronization do not fully describe the data, so next-to-leading-order
calculations matched with parton shower and hadronization models are needed to
better describe the measured distributions. Furthermore, we show that azimuthal
jet correlations are sensitive to details of the parton showering,
hadronization, and multiparton interactions. A next-to-leading-order
calculation matched with parton showers in the MC@NLO method, as implemented in
HERWIG 7, gives a better overall description of the measurements than the
POWHEG method.
