Development of potential energy surfaces for H2O+Ng van der Waals complexes

Development of potential energy surfaces for H2O + Ng van der Waals complexes Otoniel DENIS ALPIZAR! Departamento de Física, Facultad de Ciencias! Universidad de Chile Water in the Universe, Oléron island, 1-3 october 2025 Acknowledgement Funding Thierry Stoecklin! (Université de Bordeaux) Lisan Cabrera-Gonzalez (Universidad de Chile) ! Ricardo García-Vázquez (Université de Bordeaux) Ignacio Araya (Universidad de Chile) On the Importance of H₂O Collisional Data •Typical molecular clouds have low densities.! •The analysis of the observations with non-LTE models requires collisional rate coefficients with He and H2. ! •Using noble gases as proxies allows, for example, comparison with experiments. Collision Study Methodology is included in the nuclear Schrödinger equation, and the closecoupling method is employed.! Rate coefficients are computed by averaging cross sections over a Maxwell–Boltzmann distribution. V(Q) Q1 Q2 Q3 V R1 A1 r1 V1 R1 A1 r2 V2 : : : : RL AK rF-1 VN-1 RL AK rF VN V(Q1,Q2,Q3) 1. Computing a grid of ab initio energies ! (at a fixed Q)! CCSD(T), CCSD(T)-F12! aug-cc-pVTZ, aug-ccpVQZ! Molpro, Gaussian 2. Developing an interaction PES Fitting procedure of the PES: 3. Quantum Scattering Calculations Rigid Rotor: H2O+Ne & HDO+Ne H2O + Ne Averaged geometries of H2O and HDO in their ground vibrational state are different H2O 1 HDO 2 rOH rOH rOD 0.975 Å 104.41º 0.9727 Å 0.9684 Å 104.34º ∡HOH ∡HOD 1 Valironet al., JCP, 129, 134306, 2008! 2 Wiesenfeld et al., PCCP, 13, 8230, 2011 O H H Ne HDO + Ne O H H Ne Considering the principal inertia axes of HDO1 H2O + Ne Rigid Rotor: H2O+Ne & HDO+Ne ! 1 Wiesenfeld et al., PCCP, 13, 8230, 2011 Number of computed ab initio energies: ! ‣H2O+Ne: 3458! ‣HDO+Ne: 6175 Ab initio calculations for IPES Method: CCSD(T)-F12! Basis set: cc-pVTZ-F12, & cc-pVQZ-F12; extrapolated at the CBS limit! ! Program: Molpro! BSSE: corrected with counterpoise method! O H H Ne Rigid Rotor: H2O+Ne & HDO+Ne Rigid Rotor: H2O+Ne & HDO+Ne Analytical representation Ho & Rabitz, JCP, 1996, 104, 2584 H2O + Ne Rigid Rotor: H2O+Ne & HDO+Ne Analytical representation Ho & Rabitz, JCP, 1996, 104, 2584 Odd m values are now included. HDO + Ne Rigid Bender: H2O+He Towards full dimensionality 2024 2022 - Both works used the Radau coordinates for H2O. BD2 = ZD CD Summary RB: J. Chem. Phys. 154, 144307, 2021! FD: in progress RR: J. Phys. Chem. A 127, 4838, 2023! RR (HDO): Faraday Discussions, 251, 205, 2024 RB: ChemPhysChem 25, e202300752, 2024 RB: MNRAS 514, 4426, 2022 Sharing Collisional Data through BASECOL Special thanks to Marie-Lise Dubernet Thank you