DOI: 10.5061/dryad.vhhmgqp63
title: Data from: Potentials of mean force fail to describe chemical bond-breaking in solution

description: Many liquid phase studies assume that the potential energy surfaces of
 reacting molecules are the same as in the gas phase, neglecting complex
 solvent dynamics that can completely alter the nature of chemical
 reactivity. Even studies that include solvent effects typically only
 consider them in an average, equilibrium way as part of a potential of
 mean force (PMF). In this work, we use mixed quantum/classical simulations
 to compare how equilibrium and non-equilibrium solvent motions affect the
 photodissociation of a simple diatomic molecule, NaK+, in liquid
 tetrahydrofuran. A PMF analysis shows that as the excited-state molecule
 dissociates with the solvent at equilibrium, the bonding electron remains
 associated with K+ at short bond distances but eventually localizes on Na+
 at the end of dissociation.  When we examine nonequilibrium
 dynamical photodissociation trajectories, however, we find that they fall
 into three distinct categories: about a quarter of them have the bonding
 electron mainly associated with Na+, another quarter stay mainly
 associated with K+, and about half have the bonding electron shared
 roughly equally between the two ions. The results show that equilibrium
 PMFs cannot accurately describe the dynamics of bond-breaking chemical
 reactions in solution, because there is insufficient time for the solvent
 to reach equilibrium on the time scale over which bond dissociation
 occurs.
description: # Data from: Potentials of mean force fail to describe chemical
 bond-breaking in solution Dataset DOI:
 [10.5061/dryad.vhhmgqp63](10.5061/dryad.vhhmgqp63) ## Description of the
 data and file structure ### Files and variables #### File:
 repository_upload.zip **Description:**  This zip file contains this
 READ.ME and 3 folders, described below 1. eqb_PMF (folder) * Contains the
 equilibrium umbrella sampling trajectories with bond distance held at 4.00
 to 7.75 angstroms, increment by 0.25 angstroms * Sub-folder name is the
 corresponding bond distance in angstroms (e.g., the sub-folder named 4.00
 contains data for Na--K bond held at 4.00 angstroms) * Each distance
 sub-folder contains: * The xyz files (e.g., dist4.00.xyz is the xyz file
 for Na--K bond distance held at 4.00 angstroms, located in sub-folder
 4.00) * First electronic excited state wavefunction cube file
 (es_wavefunction.cube) * 1st shell THF coordination number (THF_CN.txt):
 the first column is time (in fs), the second column is Na CN, and the
 third column is K CN. 2. non_eqb (folder) * Contains 20 sub-folders (1
 through 20), corresponding to the 20 non-eqb trajectories * Within each
 sub-folder, there are the following files: * The xyz files (e.g.,
 trajec1.xyz is the xyz file for trajectory 1, located in sub-folder 1) *
 First electronic excited state wavefunction cube file
 (es_wavefunction.cube) * 1st shell THF coordination number (THF_CN.txt):
 the first column is time (in fs), the second column is Na CN, and the
 third column is K CN. 3. Other (folder) * Contains
 gas_phase_es_wavefunction.cube: * Excited state wavefunction cube file for
 NaK+ in the gas phase * Contains (i) Na0.xyz, (ii) Na1.xyz, (iii) K0.xyz,
 (iv) K1.xyz: * The xyz files for (i) single Na atom, (ii) single Na+ ion,
 (iii) single K atom, and (iv) single K+ ion, respectively, in liquid THF