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We present a comprehensive study of photoionization of OH radicals from the ground and first excited electronic states. Cross sections and asymmetry parameters for the valence orbitals are reported for photon energies from near the threshold to 60 eV. The calculations have been performed with the $R$-matrix method. Two different continuum basis types, namely, the Gaussian and $B$-spline bases, are used to assess the quality of the description of the continuum. The results show both types of continuum bases provide a similar quality description in the near threshold resonant region, but the latter can predict more reliable photoionization observables in higher-energy regions. Our calculations are compared with available experimental and theoretical results, and the discussions are provided.

The problem of photoionization of atomic hydrogen in a white-dwarf-strength magnetic field is revisited to understand the existing discrepancies in the positive-energy spectra obtained by a variety of theoretical approaches reported in the literature. Oscillator strengths for photoionization are calculated with the adiabatic-basis-expansion method developed by Mota-Furtado and O'Mahony [Phys. Rev. A 76, 053405 (2007)]. A comparative study is performed between the adiabatic-basis-expansion method and our previously developed coupled-channel theory [L. B. Zhao, O. Zatsarinny, and K. Bartschat, Phys. Rev. A 94, 033422 (2016)]. A detailed analysis of the positive-energy spectra obtained here and those from other theoretical approaches shows that the adiabatic-basis-expansion method can produce more accurate positive-energy spectra than other reported approaches for low field strengths.

The low-energy electron collisions with cyanamide molecule are investigated by using the UK molecular $R$-matrix codes for electron energies ranging from 0.01 eV to 10 eV. Three models including static-exchange, static-exchange plus polarization, and close-coupling (CC) approximations are employed to reveal the dynamic interaction. Elastic (integrated and differential), momentum-transfer, and excitation cross sections from the ground state to the three low-lying electron excited states have been presented. Two shape resonances, two core-excited resonances, and two Feshbach resonances are detected in the CC approximation. The role of active space in the target and scattering problem including the resonances is discussed. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. These resonances may be responsible for the fragments observed in a recent experiment of the dissociative electron attachments to cyanamide. Since the cyanamide molecule has a large permanent dipole moment, a Born closure procedure is used to account for the contribution of partial waves higher than $l=4$ to obtain converged cross sections.

We present a comprehensive study of the photodetachment of the negative gallium ion and elastic electron scattering from neutral Ga for photon and electron energies ranging from threshold to 12 eV. The calculations are carried out with the $B$-spline $R$-matrix method. A multiconfiguration Hartree-Fock method with nonorthogonal term-dependent orbitals is employed to generate accurate initial- and final-state wave functions. The close-coupling expansions include the $4s{\phantom{\rule{0.16em}{0ex}}}^{2}4pnl(kl)$ bound and continuum states of Ga and the $4s$-excited autoionizing states $4s4{p}^{2}$. The calculated photodetachment and elastic cross sections exhibit prominent resonance features. In order to clarify the origin of these resonances, the contributions of the major ionization channels to the partial cross sections are analyzed in detail.

We present a comprehensive study of electron collisions with boron atoms by using the $B$-spline $R$-matrix method for electron energies ranging from threshold to 100 eV. Elastic, excitation, and ionization cross sections were obtained for all transitions between the lowest 11 states of boron. A multiconfiguration Hartree-Fock method with nonorthogonal term-dependent orbitals was employed to generate accurate wave functions for the target states. Close-coupling expansions including 13, 51, and 999 physical and pseudo-target states of boron were used to check the sensitivity of the results to changes in the theoretical model. The cross-section dataset obtained from the large-scale calculations is expected to be sufficiently accurate and comprehensive for most current modeling applications involving neutral boron.