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MO-S version 1.0a is a semiempirical molecular orbital package to calculate spectroscopic properties of a molecule mainly.

Main features:

  • The semiempirical molecular orbital methods MNDO, AM1, PM3, PM5, RM1, PDDG/MNDO, PDDG/PM3, ZINDO/S, CNDO/S, CNDO/S2, CNDO/S3, and CNDO/2 are available.

  • Self-consistent field calculations using restricted Hartree-Fock (RHF), unrestricted Hartree-Fock (UHF), and restricted open-shell Hartree-Fock (ROHF) wavefunctions are available.

  • Geometry optimization using Cartesian, internal, and delocalized internal coordinates is available for RHF, UHF, and ROHF wavefunctions with the MNDO, AM1, PM3, PM5, RM1, PDDG/MNDO, and PDDG/PM3 model Hamiltonians.

  • Spectroscopic calculations with configuration interaction singles (CIS).

  • Spectroscopic calculations with random phase approximation (RPA).

  • Electron density and dipole moment in excited states available from CIS wave function.

  • Spectroscopic calculations of an open-shell system with Restricted Open-shell Hartree-Fock/CIS method (ROCIS method).

  • Frequency-dependent polarizability, α.

  • First hyperpolarizability β for Static, Electro-optic Pockels effect, Second harmonic generation and Optical-rectification β.

  • Second hyperpolarizability γ for Static, DC-electric field induced Kerr effect, DC-electric field induced second harmonics, Third harmonic generation, Degenerate four-wave mixing and DC-electric field induced optical rectification.

  • Prediction of the following molecular properties in the presence of a solvent using the SCRF calculation by means of the Onsager model:

    • Electronic spectrum using the CIS/RPA wave function.

    • Electron density and dipole moment in excited states using the CIS wave function.

    • Frequency-dependent polarizability, α, first hyperpolarizability, β, and second hyperpolarizability, γ, using the CIS wave function.

  • Analytic, Pariser-Parr, Nishimoto-Mataga, Nishimoto-Mataga-Weiss, Ohno, Ohno-Klopman, and DasGupta-Huzinaga formulas for evaluation of the two-center electron repulsion integrals are available for ZINDO/S, CNDO/S, CNDO/S2, and CNDO/S3.

  • DIIS (direct inversion in the iterative subspace) and level-shift method for improving the SCF convergence.

  • Rational function optimization (RFO) and Geometry DIIS (GDIIS) method for improving the convergence of geometry optimization.

  • Approximate Hessian (with respect to delocalized internal coordinates) for improving the convergence of geometry optimization.

  • Automatic calculation of the cavity radius for a solute.

  • Automatic input system of dielectric constant and refractive index by specifying a solvent name.

  • Rotational constants and angles between principal axes of inertia and dipole/transition moments.

  • Coordinate input format from the Gaussian Symbolic Z-matrix and the MOPAC Internal Coordinates.

MO-S is also distributed as standalone program together with MO-G.