Chemical reactions are at the core of everything that happens in the universe. From the thermonuclear fusion that powers our sun, to how antibiotics help to fight pneumonia –  everything depends on what happens when molecules collide and interact to form new compounds.

Chemist Ernesto García, based at the University of the Basque Country in Vitoria, Spain, has dedicated his academic career to understanding chemical reactions from a theoretical perspective.

“My main scientific goal is to compute accurately the efficiency of molecular processes in which molecules collide to react, dissociate, exchange energy, and deform,” says García.

García creates computational models to describe reactions that are important for studying natural phenomena or industrial processes. Having good theoretical models to predict molecular behavior means simulations will be realistic and useful for tackling research problems in the real world.

Accurate models of molecular collisions take into account many types of parameters (for example, kinetic energies, the shape of the molecules, thermal properties). García uses a workflow called Grid Empowered Molecular Simulator (GEMS) to streamline the computational work of the calculations.

GEMS was developed by the team of Antonio Laganà at the University of Perugia in Italy and is powered by high-throughput compute resources made available by the CompChem Virtual Organization.

In the last four years, García has worked in projects ranging from astronomy to applied chemistry and atmospheric science. His research has required a total of 31 million CPU hours and has resulted in eight articles in peer-reviewed journals, with more results awaiting publication.

GEMS in action

Chemical evolution of interstellar clouds

Interstellar clouds are amalgamations of gas, plasma, and dust scattered across the universe. Sergio Rampino, García, et al. recently published research that looked into how temperature influences their chemical evolution.

The team modeled the formation of C₂⁺ (an ion with a chemical bond between two carbon atoms and therefore a precursor of longer hydrocarbon chains) from one atom of carbon and the methylidine radical, CH⁺ (ubiquitous throughout the interstellar space) and found something surprising: Its rates of formation in interstellar clouds are several orders of magnitude different from the values used in current astronomical models.

Modeling nitrogen plasma

In research recently published in Plasma Sources Science and Technology, a team led by Fabrizio Esosita modeled nitrogen plasmas like those surrounding spacecraft as they enter the Earth’s or Titan’s atmosphere. Under these circumstances, the temperature can reach tens of thousands of degrees.

Thanks to the EGI grid, it was possible to calculate the collision-induced dissociation rate of the nitrogen molecules in several vibrational excited states by collision with both nitrogen atoms and nitrogen molecules.