  Classical novae are the results of surface thermonuclear explosions of
hydrogen accreted by white dwarfs (WDs) from their low-mass main-sequence or
red-giant binary companions. Chemical composition analysis of their ejecta
shows that nova outbursts occur on both carbon-oxygen (CO) and more massive
oxygen-neon (ONe) WDs, and that there is cross-boundary mixing between the
accreted envelope and underlying WD. We demonstrate that the state-of-the-art
stellar evolution code MESA and post-processing nucleosynthesis tools of NuGrid
can successfully be used for modeling of CO and ONe nova outbursts and
nucleosynthesis. The convective boundary mixing (CBM) in our 1D numerical
simulations is implemented using a diffusion coefficient that is exponentially
decreasing with a distance below the bottom of the convective envelope. We show
that this prescription produces maximum temperature evolution profiles and
nucleosynthesis yields in good agreement with those obtained using the commonly
adopted 1D nova model in which the CBM is mimicked by assuming that the
accreted envelope has been pre-mixed with WD's material. In a previous paper,
we have found that 3He can be produced in situ in solar-composition envelopes
accreted with slow rates (dM/dt < 1e-10 M_sun/yr) by cold (T_WD < 1d7 K) CO
WDs, and that convection is triggered by 3He burning before the nova outburst
in this case. Here, we confirm this result for ONe novae. Additionally, we find
that the interplay between the 3He production and destruction in the
solar-composition envelope accreted with an intermediate rate, e.g. dM/dt =
1e-10 M_sun/yr, by the 1.15 M_sun ONe WD with a relatively high initial central
temperature, e.g. T_WD = 15e6 K, leads to the formation of a thick radiative
buffer zone that separates the bottom of the convective envelope from the WD
surface.
