Highly Efficient Numerical Method for Modeling Mofs Containing Transition Metal Ions

Abstract

Employing a group-function based semiempirical approach, a new program package $\mathrm{\Sigma H\Theta \Omega }$ (seethoo), targeted to modeling of metal-organic frameworks (MOFs) containing transition metal ions (TMIs) with open d-shells is developed. In this proof of concept study it is shown that the $\mathrm{\Sigma H\Theta \Omega }$ package has potential to accurately compute d-shell low-spin (LS) —high-spin (HS) gaps and charge distributions in MOFs in $O\left(N^{1.33}\right)$ time with reasonable accuracy. The calculations were carried out for a variety of MOFs and MOF-like systems containing doubly and triply charged Mn, Fe, Co and Ni ions. For Fe-containing systems, parameters of ${}^{57}\text{Fe}$ Mössbauer spectra were also computed. For the test runs, the results reasonably agree with available experimental data up to errors introduced by use of the CNDO parametrization in the test manner.