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The initial stage of star formation is a complex area study because of itshigh density and low temperature. Under such conditions, many molecules becomedepleted from the gas phase by freezing out onto dust grains. However, thedeuterated species could remain gaseous and are thus ideal tracers. Weinvestigate the gas dynamics and NH$_2$D chemistry in eight massivepre/protocluster clumps. We present NH$_2$D 1$_{11}$-1$_{01}$ (at 85.926 GHz),NH$_3$ (1, 1) and (2, 2) observations in the eight clumps using the PdBI andthe VLA, respectively. We find that the distribution between deuteriumfractionation and kinetic temperature shows a number density peak at around$T_{\rm kin}=16.1$ K, and the NH$_2$D cores are mainly located at a temperaturerange of 13.0 to 22.0 K. We detect seven instances of extremely high deuteriumfractionation of $1.0 \leqslant D_{\rm frac} \leqslant 1.41$. We find that theNH$_2$D emission does not appear to coincide exactly with either dust continuumor NH$_3$ peak positions, but often surrounds the star-formation activeregions. This suggests that the NH$_{2}$D has been destroyed by the centralyoung stellar object (YSO) due to its heating. The detected NH$_2$D lines arevery narrow with a median width of $\rm 0.98\pm0.02 km/s$. The extractedNH$_2$D cores are gravitationally bound ($\alpha_{\rm vir} < 1$), are likelyprestellar or starless, and can potentially form intermediate-mass or high-massstars. Using NH$_3$ (1, 1) as a dynamical tracer, we find very complicateddynamical movement, which can be explained by a combined process with outflow,rotation, convergent flow, collision, large velocity gradient, and rotatingtoroids. High deuterium fractionation strongly depends on the temperaturecondition. NH$_2$D is a poor evolutionary indicator of high-mass star formationin evolved stages, but a useful tracer in the starless and prestellar cores.

Probing the initial conditions of high-mass star formation -- IV. Gas dynamics and NH$_2$D chemistry in high-mass precluster and protocluster clumps