Q-Chem Webinar 53

Q-Force: Automated parametrization of QM-based force fields using Q-Chem

Selim Sami image
Presented by Dr. Selim Sami on

Selim Sami was born in Turkey. He came to the Netherlands in 2014 upon receiving the European Master in Theoretical Chemistry and Computational Modeling scholarship and completed the degree in 2016 with honors. In 2020, he obtained his Ph.D. degree with honors from the University of Groningen (The Netherlands) under the supervision of Remco Havenith and Ria Broer. During his Ph.D., he worked on the prediction of dielectric properties of organic materials for photovoltaic applications and was also the main developer of Q-Force, which derives molecular dynamics force fields from quantum mechanical calculations. Afterward, he joined Shirin Faraji’s group at the University of Groningen, to work on the extension of Q-Force to excited states and its interface with Q-Chem. Since April 2021, he has been working with Siewert-Jan Marrink (University of Groningen) on a reactive Martini force field and the extension of Q-Force to coarse models like the Martini force field.


The quality of molecular dynamics simulations strongly depends on the accuracy of the underlying force fields (FFs) that determine all intra- and intermolecular interactions of the system. Commonly, transferable FF parameters are determined based on a representative set of small molecules. However, such an approach sacrifices accuracy in favor of generality.

Here, an open-source and automated toolkit named Q-Force is presented, which augments these transferable FFs with molecule-specific parameters that are derived from quantum mechanical (QM) calculations. The molecular fragmentation procedure allows treatment of large molecules (> 200 atoms) with low computational cost. The generated Q-Force FFs can be used at the same computational cost as transferable FFs, but with improved accuracy. Overall, the accuracy, user-friendliness, and minimal computational overhead of the Q-Force protocol, make it widely applicable for atomistic molecular dynamics simulations.

In this webinar, we will introduce the methodology and demonstrate the improved accuracy of Q-Force FFs on the vibrational properties and the potential energy surfaces of a selection of molecules. Additionally, we will discuss the interface of Q-Force with Q-Chem and demonstrate it with a hands-on example.

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