SYSMOIC is a research, non-commercial, program package for the calculation and graphical visualization of a number of time-independent (static) and time-dependent (dynamic) magnetic and electric molecular property densities, which are invariant with respect to the choice of the reference origin. Static magnetic molecular properties are formulated in terms of the magnetically induced current density, whose independence from the origin is guaranteed by the (CTOCD) method. For the interaction with optical fields, dynamic molecular properties are obtained from either the current density induced by the time-dependent magnetic field or the time derivative of the electric field of the radiation. In both cases the origin independence of the current densities and derived property densities is ensured.
The procedures described in this guide can be applied to closed-shell molecular systems at the Density Function Theory (DFT) level of approximation as well as at the Hartree-Fock (HF) level. The extension to open shell systems and the inclusion of the electron correlation at CCSD level is available for a restricted number of properties. Work is underway to expand their availability.
More precisely, the package provides methods for the calculation of the quantum mechanical, second-rank electron current density tensor (CDT), which is used to calculate the first-order current density vector , for any orientation of an inducing external, static or time-dependent magnetic field. The current density induced by the time-derivative of the electric field of an external radiation can also be determined, along with a number of related density properties, such as the dynamic electric dipole polarizability density and the specific optical rotation power density, see for example here. Aromaticity indicators such as bond current strengths, NICS, ACID and AACID maps, vorticity tensor (VT) and anisotropies of both CDT and VT can also be calculated and visualized.