The Dalton quantum chemistry program system

Abstract

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.

FIGURE 1

The absolute value of the indirect spin–spin coupling constants (Hz, greater than 0.1 Hz) in valinomycin (left), on a logarithmic scale as a function of the internuclear distance (pm). We have used blue, black, red, and green for the CH, CC, CO, and CN coupling constants, respectively. The spin–spin coupling constants have been calculated at the LDA/6-31G level of theory. (Reproduced with permission from Ref 54. Copyright 2004, John Wiley & Sons, Ltd.)

FIGURE 2

Near-edge X-ray absorption fine structure (NEXAFS) study of Gd acetate nanoparticles. The experimental spectrum (top) is compared with the sum of the theoretical spectra (black) for isolated acetate (green) and a coordination complex (red). (Reproduced with permission from Ref 105. Copyright 2012, Springer.)

FIGURE 3

One- and two-photon absorption spectra for channelrhodopsin calculated using the polarizable embedding method implemented in Dalton. The insert on the top of the right hand side shows the protein embedding potential projected onto the molecular surface.

FIGURE 4

Left: The titin-I27 domain highlighting the disulfide bridging bond and a schematic representation of the stretching of the polyprotein strain by the aid of the atomic force microscopy; right: the titin-I27SS model, designed to model the redox-active site in the titin-I27 domain.

FIGURE 5

MP2 study of insulin (787 atoms) in the cc-pVDZ basis (7,604 orbitals). Left: Localized orbitals obtained by minimizing the second power of the orbital variances. The least local occupied (blue) and least local virtual (red) orbitals are plotted using orbital contour values of 0.01 a.u. Right: MP2 electrostatic potential calculated using the DEC scheme plotted on an isodensity surface (0.001 a.u.). The values are indicated by the color box (a.u.).