Hydrogen bonding has been extensively studied by both experimental and theoretical methods [Journal of Physics: Condensed Matter, 17, 8, 2002]. Over the last two decades X-ray spectroscopy has proven to be a powerful technique to probe the complex dynamics of hydrogen bonding formation in liquids. In a recent study [Physical Chemistry Chemical Physics, 17, 40, 2015] X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) were used to investigate the influence of hydrogen bonding on the electronic structure of ammonia in the solution phase. Significant spectral differences in the XAS and RIXS spectra of aqueous and gas phase ammonia were attributed to the orbital mixing with water orbitals, dipole-dipole interactions, differences in vibronic coupling and nuclear dynamics on the time-scale of RIXS processes. For understanding of these complex phenomena comprehensive modeling of electron-nuclear dynamics in isolated core-excited molecule is required as the first step. Here we aim to carry out high-quality theoretical study of quasi-elastic vibrationally-resolved RIXS via three lowest core-excited electronic states in ammonia: N1s-1:4a1+1, and double degenerated N1s-1:2e+1 states. To construct the core-excited state potential energy surfaces (PESs) we use will use ab initio methods based on the algebraic diagramatic construction (ADC(2)-x) scheme for the polarization propagator. This scheme describes the excited electronic states and related properties based on the Møller-Plesset perturbation theory partition of the hamiltonian. These PESs will be then used to model nuclear dynamics in RIXS via two complementary quantum approaches: i) Time-dependent solution of the Schodinger equation (wavepacket propogation technique) and ii) Time-independent approach using Kramers-Heisenberg equation for vibrational degrees of freedom. Unusual dispersion dependencies of the vibrational lines on the decay channel back to the ground electronic state (i.e., quasi-elastic scattering channel) which are observed in the experiments will be explored through theoretical modeling. Our results will give new insights into the quantum phenomena that is observed in ultrahigh resolution gas-phase RIXS experiments and will be the background for understanding of nuclear dynamics, providing crucial information about the nature of hydrogen-bonding in liquids.