There exist two main paths to calculate the thermochemistry properties of a molecule: using a single calculation or a composite approach. In this project, a composite approach developed in the past by the group called correlation consistent composite approach (ccCA) is used to determine the enthalpy of formation and dissociation energy of transition metal complexes. For such compound an alternative of ccCA: the relativistic pseudopotential ccCA (rp-ccCA) is preferred to include relativistic effect in a much cheaper way. Moreover, density functional theory (DFT) is also used as single method to provide comparison point with our composite approach. DFT is applied for transition metal, lanthanide and actinide whereas rp-ccCA is for now applied for transition metal.

Lanthanide
Basis set for therochemistry

Our group is developing methods for quantum dynamics including a non Born-Oppenheimer approach to coupled electron-nuclear dynamics, the Multiconfiguration Electron-Nuclear Dynamics (MCEND) method. With this method we can analyze cases where the motion of the nuclei cannot be uncoupled from the electronic motion, and vice versa. This is important in fields such as attosecond spectroscopy field, where electron-nuclear interactions must be accounted for. Particular applications include modelling charge-resonance enhanced electronic processes or high-order harmonic generation where UV-vis pulses are used to generate attosecond laser pulse. A video sample of the electron density during an MCEND simulation of high harmonic generation for the H₂ molecule, is shown to the right.

MCEND

Molecular dynamics (MD) is commonly used to simulate macromolecular structure and dynamics. Biological and chemical systems at the atomistic level on timescales ranging from femtoseconds to milliseconds can be studied. In classical MD, Newtonian mechanics are used to study the motions and interactions of atoms and molecules within the system. The initial velocity of the atoms in the system is assigned randomly according to the Boltzmann distribution function and the accelerations are calculated by the forces acting on each atom. Algorithms such as “Leapfrog” are used to update velocities and positions of the atoms within the ensemble at each timestep. By iterative update of the positions simulation trajectories which contain the information regarding dynamics of the system are generated.

SAMPL6

Synthesis of glycopeptide

The goal of this project is to study the electron dynamic and their interaction with an electromagnetic field. To do so time-dependent methods are used however, most of the TD methods depends on one single-excited wave-function. In this project, a multi-excited wave-function is built through the time-dependent configuration interaction (TDCI) method. Such method allows a better representation of the wave-function when propagated over time. Molecular properties such as: dipole moment, static polarizabilities and excitation energy can be determined using that method.

TDCI

The Per-and Polyfluoroalkyl substances are an important issue for the environment as they can not degrade easily. Moreover, most of the properties for these molecules and their derivatives are unknown, and so need to be assessed. In this project, molecular dynamic is used to study the binding site of different PFAS on different protein present in the Great Lakes fishes as well as on human proteins. Furthermore, quantum molecular calculations are carried on to investigate the different properties of the PFAS molecules (pKa, LogS, etc.).

Carbon dioxide (CO₂) emissions have been increasing since the start of industrialization. A strategy to reduce the amount of CO₂ is called post-combustion carbon capture (PCC). PCC is one of the most widely studied CCS methods due to its ability to be adapted to current CO₂ emission sources. Chemical absorption, a popular PCC method, involves a temperature dependent reversible reaction between CO₂ and a solvent. Common solvents used are amine based but these have several drawbacks including the degradation of the amine and production of toxic byproducts. Amino acid salt solutions are alternative solvents that share many advantages with common amine solvents but without many of the drawbacks. This project investigates the ideal mixture of amino acid salts for optimal CO₂ absorption from flue gas utilizing reaction ensemble Monte Carlo simulations.