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The theory of nuclear ring currents of torsional molecules induced by an external magnetic field along the torsion axis was developed in the preceding paper [D. Jia et al., preceding paper, Phys. Rev. A 106, 042801 (2022)]. Here we study the magnetically induced electronic current density (MIC) for toluene in the presence of an external magnetic field that is aligned with the torsion axis of the methyl group. Properties of the MIC are studied in detail at the density-functional theory (DFT) level using our gauge-including magnetically induced current method, the derivation of which is briefly outlined. The strength of the MIC is determined by numerical integration and compared to the estimated strength of the magnetically induced nuclear ring current reported in the preceding paper. Spatial contributions to the diatropic and paratropic MICs are discussed in detail, where the diatropic MIC flows in the classical direction and the paratropic MIC flows in the opposite direction. The MIC in the vicinity of the methyl group is mainly diatropic, whereas the phenyl group ring is dominated by a paratropic MIC of -14.90 nA T-1 localized to the carbon atoms. The strength of the MIC near the methyl group is 10.41 nA T-1, which is of about the same size as the strength of the ring current of benzene when the magnetic field is perpendicular to the molecular ring. The strength of the magnetically induced nuclear ring current of the whole toluene molecule is 19.9 pA T-1, which is two orders of magnitude smaller than the electronic one of -1.93 nA T-1 calculated for the eclipsed structure at the employed DFT level. This value is in perfect agreement with the current strength of -1.93 nA T-1 calculated at the coupled-cluster singles and doubles level with a perturbative treatment of the triple excitations. The current strength calculated at the second-order Moller-Plesset perturbation level is 1.20 nA T-1, which is of the same size with opposite sign.

We develop the theory of nuclear ring currents induced by external magnetic fields in torsional molecules. The theory is applied to toluene, whose torsion axis is oriented along the magnetic field. We obtain magnetically induced diatropic and paratropic contributions to the nuclear ring current flowing in the classical and nonclassical directions, respectively. In the electronic and torsional and rotational ground state of toluene, the strengths of the diatropic and paratropic nuclear ring-current susceptibilities are -19.9 pA/T and 0.4 fA/T, respectively, yielding a net current strength of -19.9 pA/T. The paratropic contribution is very small because the torsional barrier of toluene is very low. The study suggests criteria for observing significant magnetically induced nuclear ring currents in torsional molecules whose axis is oriented along the magnetic field.

Optimal control theory is used to design ultrashort (subpicosecond) infrared laser pulses inducing state-selective vibrational excitation processes. For a Thiele-Wilson model Hamiltonian with parameters adapted for the HDO molecule, complete control of vibrational excitation by such pulses is demonstrated, including the selective excitation of OH or OD local vibrations (mode or bond selectivity). It is also shown how the constraint of fluence minimization can be used to achieve the additional objective of keeping the laser intensity as low as possible. We find that the approach works well from a computational point of view, and no numerical difficulties are encountered in a conjugate-gradient implementation of the pulse optimization. The spectral composition of the resulting minimum-fluence pulses follows a simple pattern