Disciplines
Computational Chemistry | Physical Chemistry
Abstract (300 words maximum)
Proton transfer (PT) from one molecule to another is among the most studied phenomena in chemistry. PT requires the bond cleavage and the formation of a new one, AH+ + B -> A+ BH+. In protonated water clusters, such a process consists of the interconversion of hydrogen bonds. Experimentally, such a process can be observed as a significant increase of a dipole moment. However, other vibrational transitions often occur with small changes in the dipole moment while large changes in polarizability. In this work, we study the PT process in a protonated water cluster, H7O3+ using computational methods. We run geometry optimization and compare data of various methods, such as density functional theory (DFT) methods and highly accurate CCSD(T) level of theory, with available experimental data. Thermodynamic data of H7O3+ and its dissociation fragments, H5O2+, H3O+, and H2O are collected, and dissociation energies are calculated. Also, harmonic vibrational infrared (IR) and Raman spectra of H7O3+are calculated using normal mode analysis and compared to anharmonic spectra obtained from molecular dynamics simulations. Raman spectra of H7O3+ have yet to be recorded in the experiment. The second-order Møller–Plesset perturbation theory (MP2), Becke 3-Parameter Lee-Yang-Parr functional (B3LYP), Perdew-Burke-Ernzerhof (PBE) functional, and the Coupled Cluster theory are used in conjugation with AVDZ and AVTZ basis sets. IR and Raman spectroscopies are used to identify vibrational modes of a complex that cause changes in dipole moment and polarizability, respectively. Collected data on H7O3+ will aid in the determination of the polarizability tensor surface. H7O3+ and H5O2+ dissociation energies and their corresponding zero-point corrected values will be compared to the experimental values of Dalleska et. al. Dissociation energies provide insight into the strength of bonds in a molecular complex and reveal the accuracy of the given computational approach. Identifying anharmonic shifts and new vibrational modes in the vibrational spectra can aid in the understanding of the structure and interactions of the clusters. The shifts in spectra are due to the interactions between the clusters and their surroundings, as well as the symmetry of the molecules. The study of this small, protonated water cluster, H7O3+ is integral to the study of proton motion in biological and synthetic systems.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Martina Kaledin
Computational study of the proton transfer in the H7O3+ cluster
Proton transfer (PT) from one molecule to another is among the most studied phenomena in chemistry. PT requires the bond cleavage and the formation of a new one, AH+ + B -> A+ BH+. In protonated water clusters, such a process consists of the interconversion of hydrogen bonds. Experimentally, such a process can be observed as a significant increase of a dipole moment. However, other vibrational transitions often occur with small changes in the dipole moment while large changes in polarizability. In this work, we study the PT process in a protonated water cluster, H7O3+ using computational methods. We run geometry optimization and compare data of various methods, such as density functional theory (DFT) methods and highly accurate CCSD(T) level of theory, with available experimental data. Thermodynamic data of H7O3+ and its dissociation fragments, H5O2+, H3O+, and H2O are collected, and dissociation energies are calculated. Also, harmonic vibrational infrared (IR) and Raman spectra of H7O3+are calculated using normal mode analysis and compared to anharmonic spectra obtained from molecular dynamics simulations. Raman spectra of H7O3+ have yet to be recorded in the experiment. The second-order Møller–Plesset perturbation theory (MP2), Becke 3-Parameter Lee-Yang-Parr functional (B3LYP), Perdew-Burke-Ernzerhof (PBE) functional, and the Coupled Cluster theory are used in conjugation with AVDZ and AVTZ basis sets. IR and Raman spectroscopies are used to identify vibrational modes of a complex that cause changes in dipole moment and polarizability, respectively. Collected data on H7O3+ will aid in the determination of the polarizability tensor surface. H7O3+ and H5O2+ dissociation energies and their corresponding zero-point corrected values will be compared to the experimental values of Dalleska et. al. Dissociation energies provide insight into the strength of bonds in a molecular complex and reveal the accuracy of the given computational approach. Identifying anharmonic shifts and new vibrational modes in the vibrational spectra can aid in the understanding of the structure and interactions of the clusters. The shifts in spectra are due to the interactions between the clusters and their surroundings, as well as the symmetry of the molecules. The study of this small, protonated water cluster, H7O3+ is integral to the study of proton motion in biological and synthetic systems.