- Excited condensed state electrons drive essential chemistry.
- Electron force field makes feasible simulations of large scale excited electron dynamics.
- (a) Excited condensed system evolves through many curve crossings, and can be approximately described by a mean field trajectory. (b) However, the mean field trajectory may incorrectly bisect well-separated adiabatic states.
- Summary of electron force field development.
- Character of electron depends on its proximity to nuclei.
- Gaussian and exact wave packet dynamics match for free particle and harmonic oscillator potentials.
- Exact and Gaussian wave packet dynamics for a double well potential.
- In sparse systems, electrons move mostly along adiabatic paths, with crossings limited to conical intersections with reduced dimensionality.
- potential energy surface (kcal/mol); eFF properly dissociates , but the simplicity of the basis leads to underbinding.
- Pauli repulsion comes from the kinetic energy increase upon making orbitals orthogonal to each other.
- Comparison of Pauli repulsion and electrostatic repulsion between two wavefunctions with .
- eFF geometries of simple substituted hydrocarbons
- eFF geometries of larger hydrocarbons, bond lengths in Angstroms
- Multiple bonds can split or form symmetric ``banana'' pairs.
- eFF reproduces curved bonds of cyclopropane, and pucker of five and six membered rings.
- eFF reproduces steric repulsions within alkanes
- eFF reproduces allylic strain interaction
- In eFF, methyl cation and radical are stable but methyl anion is unbound
- Protonation of helium and ammonia
- Carbocations can rearrange via hydride or methyl shifts.
- eFF distinguishes between allowed and forbidden hydrogen reactions.
- eFF can account for ionic and multicenter bonding.
- Previously proposed plasma phase transition [42,43] where hydrogen dissociates and ionizes simultaneously
- Dynamics snapshots showing deuterium dissociation as temperature is raised.
- Proton-proton pair distribution function shows gradual dissociation.
- Equation of state ( = 2 bohr) shows good agreement with best available theory.
- High densities suppress ionization that occurs at high temperature.
- Reproduction of the experimental shock Hugoniot curve obtained by gas gun and Z machine; Nova laser remains an outlier.
- Core holes relax via a two stage Auger decay process.
- Red points compare Boys localized Hartree-Fock orbital energies to eFF orbital energies.
- Removal of valence electrons from ethane results in selective bond breaking.
- Electron energies show Auger process in adamantane in detail.
- Auger dissociation of methane and ethane following creation of a core hole.
- Auger dissociation of neopentane and adamantane following creation of a core hole.
- We remove a core electron from a central carbon of a diamondoid particle.
- Trajectories of electrons after removal of a core electron.
- Excited electrons dissipate their energy into their surroundings.
- Pauli interaction between -like versus -like electrons.
- Pauli repulsion between -like electrons is modified to make electron sizes more similar and prevent electron-electron coalescence.
- Valence electrons of boron through neon arrange themselves into symmetric shells.
- The new eFF reproduces the correct periodic trend of ionization potentials for hydrogen through neon, while the old eFF is only suitable for describing hydrogen through carbon.
- The new eFF computes reasonable polarizabilities for first-row atoms. Oxygen and fluorine are exceptional cases, as the eFF gives those two atoms a permanent dipole moment which they should not have.
- eFF describes both open-shell and closed-shell atom hydrides properly.
- Atom hydride bond lengths and angles.
- Atom hydride bond dissociation energies.
- Measuring electron-nuclear distances and the angle between lone pairs.
- Comparison of eFF electron positions versus B3LYP localized orbital positions. There is good agreement, except that eFF lone pairs are further away from the nucleus than B3LYP lone pairs.
- Electron densities along lone pairs and bond pairs; a comparison between eFF electron densities and B3LYP localized orbital electron densities.
- Electron arrangements in carbon-carbon single, double, and triple bonds.
- Bond dissociation energies and geometry parameters of ethane, ethylene, and acetylene.
- Improved geometries for old eFF ``problem hydrocarbons''.
- Key geometric parameters of substituted alkanes and alkenes.
- Comparison of old versus new eFF geometric parameters for simple substituted alkanes and alkenes.
- Optimized eFF and B3LYP alkenes superimposed, with root-mean-squared deviations (RMSD) given in parenthesis (angstroms).
- eFF overestimates the energy gained from turning double bounds into single bonds; prototype and cycloadditions are shown, eFF (B3LYP) energy differences in kcal/mol.
- eFF alkynes are unstable relative to alkene diradicals. eFF (B3LYP) distances in angstroms.
- eFF shows no resonance stabilization of conjugated double bonds.
- Gallery of heteroatom single, double, and triple bonds.
- Bonds between heteroatoms are too strong and too short, possibly due to insufficient repulsion between lone pairs.
- Repulsion between neon atoms in eFF is too small.
- Hydrogen bonds in eFF are too strong and too short, probably from a combination of too-small Pauli repulsion and too-large monomer dipoles.
- Interaction energy of the water dimer, with the estimated effects of changing monomer dipole moments and Pauli repulsions to be the correct values.
- The new eFF creates spurious stable minima corresponding to unphysical arrangements of hydrogen atoms.
- Icosahedral boron cluster is stable with the new eFF, and matches a B3LYP optimized geometry well; however an amorphous boron-centered structure is found to be even more stable.
- Uniform electron gas represented as different packings of localized electrons.
- Uniform electron gas energy versus density. eFF with exchange matches Hartree-Fock, while eFF with exchange and correlation matches exact quantum Monte Carlo energies.
- Density versus electron size. Adding correlation causes the electrons to grow larger.
- Survey of electron packings considered, showing a variety of packing fractions and coordinations.
- Energetics of different electron packings, with non-close-packed configurations marked red, and close-packed configurations marked black. All close-packed arrangements have similar energies which are near the exact values.
- Spin-averaged electron-electron pair distribution function, showing partial explicit segregation of electrons in eFF.
- Spin-resolved electron-electron pair distribution functions, showing that eFF keeps same-spin electrons apart, but allows opposite-spin electrons to mingle.
- Electron trajectories in a uniform electron gas ( = 2 bohr) at low and high temperature.
- At low temperatures, the heat capacity of a metal goes to zero because only electrons near the Fermi level are excited.
- eFF uniform electron gas has the heat capacity of a solid crystal, not a metal with Fermi-Dirac statistics. The heat capacity in this figure is given by the slope, since we are plotting total energy versus temperature.
- Plasma oscillations are excited uniformly over the range of temperatures considered.
- We modify the exchange interaction to fit properly the interaction energy of and HeH.
- Comparison of the new exchange potential to previous Pauli potentials, showing that the new potential has a reasonable amount of repulsion.
- We scale the correlation function to match the long range falloff of the GVB correlation energy in .
- Comparison of potential energy curves; we limit the correlation function to correcting correlation, not deficiencies in the basis.
- Gallery of systems with nuclei and s-like electrons.
- eFF with exchange shows good agreement with Hartree-Fock for bond lengths and dissociation energies of s-electron systems.
- eFF reproduces some energy and bond length changes caused by adding correlation.
- Atomic correlation energies, eFF reproduces major trends.

Julius 2008-04-29