Potential energy surface

About: Potential energy surface is a research topic. Over the lifetime, 11674 publications have been published within this topic receiving 307691 citations.

Existence of Posner's Cluster in Vacuum

Abstract: Using ab initio methods, a single isomer of D3h symmetry was found to be preeminent on the Ca3(PO4)2 cluster potential energy surface. This isomer has the distinct feature that each calcium atom is surrounded by four oxygen atoms. We studied the aggregation of this isomer in the [Ca3(PO4)2]n systemwith n being 2 or 3. This gives us an energy reference for analyzing the stability of the so-called Posner's cluster Ca9(PO4)6 which is the core of the actual structural model of amorphous calcium phosphate. Posner's cluster is shown to be significantly stabilized in comparison to the energy reference.

Origin of the Transition State on the Free Energy Surface: Intramolecular Proton Transfer Reaction of Glycine in Aqueous Solution

Abstract: Not only to elucidate the origin of the reaction barrier in liquid phase, i.e., the free energy of activation, but also to locate the proper transition state (TS) for a chemical reaction, the molecular dynamics method and the free energy perturbation theory have been applied to the intramolecular proton transfer reaction of glycine in aqueous solution, i.e., the zwitterion (ZW), to the neutral form (NF). The potential energy surface varies drastically as its environment changes from gas phase to aqueous solution, and experimentally, the existence of an entropy barrier is also suggested due to the solvent molecules. In this study, it is reported that the TS on the free energy surface (FES) corresponds approximately to the geometry at s ≈ 0.66 amu1/2 bohr, where s denotes the intrinsic reaction coordinate (IRC) for the gas-phase reaction, and therefore, the TS geometry is completely different from that for the gas phase. The free energy difference between ZW and NF is 8.46 ± 1.45 kcal/mol, and then the free...

Multidimensional effects on dissociation of N2 on Ru(0001).

Abstract: The applicability of the Born-Oppenheimer approximation to molecule-metal surface reactions is presently a topic of intense debate. We have performed classical trajectory calculations on a prototype activated dissociation reaction, of N2 on Ru(0001), using a potential energy surface based on density functional theory. The computed reaction probabilities are in good agreement with molecular beam experiments. Comparison to previous calculations shows that the rotation of N2 and its motion along the surface affect the reactivity of N2 much more than nonadiabatic effects.

Trajectory study of the reaction O(1D2)+HCl→OH+Cl on a fitted ab initio surface

Abstract: We performed a classical trajector study of the reaction O(1D)+HCl→Cl+OH using an analytical potential energy surface fitted to extensive ab initio calculations. The reactions proceed via long‐living HOCl complexes before breaking up into products. Because no barrier is present for insertion pathways the total cross section is a decreasing function of the energy. The vibrational OH distribution is inverted and peaks at ν′=2–3. The ratio P(ν′=1)/P (ν′=0) is 1.42 and agrees very well with the experimental value of 1.5. The rotational OH distribution within the vibrational ground state is highly inverted, peaks at about j′=28, and is in good agreement with recent experimental data. The angular OH distribution is slightly forward peaked. The results for O(1D)+HCl→Cl+OH are compared with those for the similar reaction O(1D)+H2→H+OH.