Kristian O. Sylvester-Hvid

The Dalton quantum chemistry program system

Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic‐structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge‐origin‐invariant manner. Frequency‐dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one‐, two‐, and three‐photon processes. Environmental effects may be included using various dielectric‐medium and quantum‐mechanics/molecular‐mechanics models. Large molecules may be studied using linear‐scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms.

Nonlinear optical response of molecules in a nonequilibrium solvation model

The response equations governing nonequilibrium solvation in the continuum approach are derived and implemented for second order in response theory. Applications to a simple benchmark system consisting of a solvated water molecule are presented. We consider the role of nonequilibrium solvent configurations on the first hyperpolarizability. Effects of solvation parameters, such as optical and static dielectric constants, and frequency dispersion are discussed.

Excited state polarizabilities in solution obtained by cubic response theory: Calculations on para-, ortho-, and meta-nitroaniline

We show that response theory implemented with a self-consistent reaction field theory model is a viable approach to simulate excited state polarizabilities of molecules in solution. The excited sta ...

The Cotton–Mouton effect of liquid water. Part II: The semi-continuum model

We present gauge-origin independent calculations of the Cotton‐Mouton effect of liquid water. The liquid is represented by a semi-continuum model such that the central molecule is surrounded by its first solvation shell, which explicitly accounts for the strong interaction between the water molecule of interest and its closest neighbors. The long-range interactions with the solvent are modeled by a dielectric continuum surrounding the water molecule and the first solvation shell. We employ large basis sets, using London atomic orbitals in order to obtain gauge-origin independent results close to the Hartree‐Fock limit. It is demonstrated that the direct interaction between neighboring molecules leads to a large effect on the calculated Cotton‐Mouton constant, which undergoes a sign change from the gas to liquid phase, as observed previously for the linear electro-optical effect @K. V. Mikkelsen et al., J. Chem. Phys 102, 9362 ~1995!#. Our best estimate for the molar Cotton‐Mouton constant, 238.1i10 220 G 22 cm 3 mol 21 ~corrected for local field effects!, is in reasonable agreement with the experimental value of 2118(15)i10 220 G 22 cm 3 mol 21 . We expect that the remaining discrepancy is mainly due to an inadequate treatment of electron correlation.

Hyperpolarizability depolarization ratios of nitroanilines

The depolarization ratios for the first hyperpolarizabilities of para-, meta-, and ortho-nitroanilines have been calculated in gas and solution phases. The results resolve ambiguities in the interpretation of experimental results for these quantities, and pinpoint the actual problems in previous simulations. It is argued that extraction of individual components of β of low symmetry molecules from experimental depolarization measurements alone is difficult, and that the support from simulations to extract the proper information is indispensable in most cases.