AIQM1 (artificial intelligence–quantum mechanical method 1) is a general-purpose method approaching the gold-standard coupled cluster quantum mechanical method with high computational speed of the approximate low-level semiempirical quantum mechanical methods for the ground-state, closed-shell species, but also transferable for calculation of charged and radical species as well as for excited-state calculations with a good accuracy. See AIQM1 preprint on ChemRxiv for more details.

Strengths: AIQM1 is especially good for energy calculations and geometry optimizations of ground-state neutral compounds.

Limitations: This method is currently limited to compounds only containing H, C, N, and O elements.

Availability: AIQM1 is available in MLatom package interfaced to the MNDO program, TorchANI, and dftd4. Some features also require interfaces to the Gaussian or ASE packages.



To use AIQM1 and related methods (AIQM1@DFT and AIQM1@DFT*) you need MLatom version 2.1 (to be released in coming days) or newer. See download and manual pages on this website for instructions.


The free binary and open-source code of the MNDO program is available from the official distributors of the MNDO code as described at



Optional packages for additional features


To perform AIQM1 calculations, you can provide input files with appropriate options to MLatom (command line options also supported) and then run MLatom calculations as usual (see manual and tutorial pages on this website). Below we provide examples of some typical uses.

Get started: Simplest calculation job

to be continued…

mlatom [options]

Geometry optimization

Calculation of heats of formation

Calculations of charged species and radicals

Vertical excitation energies

Excited-state geometry optimization