Dynamics of excitation and electron capture processes in the H+ + H(1s) collision system in a Debye plasma is studied as an example of collision systems with screened Coulomb interactions. The two-centre atomic orbital close-coupling method (TC-AOCC) was used with a basis containing all n ⩽ 6 and 7s discrete and 99 quasi-continuum states centred on the target and all n ⩽ 3 discrete states centred on the projectile when describing the excitation process, and vice versa when describing the electron capture. The atomic orbitals and energies of all one-centre states have been determined variationally as a function of screening parameter and used to calculate the state-selective electron capture and excitation cross sections. With an increase of the screening, the bound states successively enter the continuum, thereby reducing the number of reaction channels in the discrete spectrum. The effect of interaction screening on the direct and exchange electronic couplings is also strong. Both these factors significantly affect the dynamics of electron capture and excitation processes. The interaction screening parameter can, thus, be used as a tool for control of the collision dynamics.