  The interaction picture in a non-Hermitian realization is discussed in detail
and considered for its practical use in many-body quantum physics. The
resulting non-Hermitian interaction-picture (NHIP) description of dynamics, in
which both the wave functions and operators belonging to physical observables
cease to remain constant in time, is a non-Hermitian generalization of the
traditional Dirac picture of standard quantum mechanics, which itself is widely
used in quantum field theory calculations. Particular attention is paid here to
the variational (or, better, bivariational) and dynamical (i.e.,
non-stationary) aspects that are characteristic of the coupled cluster method
(CCM) techniques that nowadays form one of the most versatile and most accurate
of all available formulations of quantum many-body theory. In so doing we
expose and exploit multiple parallels between the NHIP and the CCM in its
time-dependent versions.
