Estimating successive pKa values of polyprotic acids from ab initio molecular dynamics using metadynamics: the dissociation of phthalic acid and its isomers

2015 ◽  
Vol 17 (9) ◽  
pp. 6383-6388 ◽  
Author(s):  
Anil Kumar Tummanapelli ◽  
Sukumaran Vasudevan
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio ◽  
Phthalic Acid ◽  
Ab Initio Molecular Dynamics ◽  
Pka Values

pKa values of polyprotic acids estimated from ab initio molecular dynamics computation of the change in free energy upon dissociation.

scholarly journals Water Dipole and Quadrupole Moment Contributions to the Ion Hydration Free Energy by the Deep Neural Network Trained with Ab Initio Molecular Dynamics Data

2020 ◽  
Author(s):  
YU SHI ◽  
Carrie C. Doyle ◽  
Thomas L. Beck
Keyword(s):  
Neural Network ◽  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio ◽  
Deep Neural Network ◽  
Ab Initio Molecular Dynamics ◽  
Quadrupole Moments ◽  
Hydration Free Energy ◽  
Ion Hydration ◽  
Water Dipole

<div>We report a calculation scheme on water molecular dipole and quadrupole moments in the liquid phase through a Deep Neural Network (DNN) model. Employing the the Maximally Localized Wannier Functions (MLWF) for the valence electrons, we obtain the water moments through a post-process on trajectories from \textit{ab-initio} molecular dynamics (AIMD) simulations at the density functional theory (DFT) level. In the framework of the deep potential molecular dynamics (DPMD), we develop a scheme to train a DNN with the AIMD moments data. Applying the model, we calculate the contributions from water dipole and quadrupole moments to the electrostatic potential at the center of a cavity of radius 4.1 \AA\ as -3.87 V, referenced to the average potential in the bulk-like liquid region.</div><div>To unravel the ion-independent water effective local potential contribution to the ion hydration free energy, we estimate the 3rd cumulant term as -0.22 V from simulations totally over 6 ns, a time-scale inaccessible for AIMD calculations. </div>

scholarly journals Exploring the free energy surface using ab initio molecular dynamics

2016 ◽  
Vol 144 (16) ◽  
pp. 164101 ◽  
Author(s):  
Amit Samanta ◽  
Miguel A. Morales ◽  
Eric Schwegler
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio ◽  
Energy Surface ◽  
Ab Initio Molecular Dynamics ◽  
Free Energy Surface

scholarly journals Ultrafast proton transport in water-methanol mixtures

2019 ◽  
Vol 205 ◽  
pp. 09004
Author(s):  
Maria Ekimova ◽  
Felix Hoffmann ◽  
Gul Bekcioglu-Neff ◽  
Aidan Rafferty ◽  
Erik T. J. Nibbering ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Proton Transport ◽  
Ab Initio Molecular Dynamics ◽  
Transport Pathway ◽  
Pump Probe ◽  
Dynamics Simulations

Femtosecond UV/IR pump-probe experiments and ab initio molecular dynamics simulations of 7-hydroxyquinoline in water-methanol mixtures demonstrate an unexpectedly dominant OH-/CH3O- transport pathway but consistent with a solvent-dependent photoacidity free energy-reactivity correlation behaviour.

scholarly journals Water Dipole and Quadrupole Moment Contributions to the Ion Hydration Free Energy by the Deep Neural Network Trained with Ab Initio Molecular Dynamics Data

2020 ◽  
Author(s):  
YU SHI ◽  
Carrie C. Doyle ◽  
Thomas L. Beck
Keyword(s):  
Neural Network ◽  
Molecular Dynamics ◽  
Free Energy ◽  
Ab Initio ◽  
Deep Neural Network ◽  
Ab Initio Molecular Dynamics ◽  
Quadrupole Moments ◽  
Hydration Free Energy ◽  
Ion Hydration ◽  
Water Dipole

<div>We report a calculation scheme on water molecular dipole and quadrupole moments in the liquid phase through a Deep Neural Network (DNN) model. Employing the the Maximally Localized Wannier Functions (MLWF) for the valence electrons, we obtain the water moments through a post-process on trajectories from \textit{ab-initio} molecular dynamics (AIMD) simulations at the density functional theory (DFT) level. In the framework of the deep potential molecular dynamics (DPMD), we develop a scheme to train a DNN with the AIMD moments data. Applying the model, we calculate the contributions from water dipole and quadrupole moments to the electrostatic potential at the center of a cavity of radius 4.1 \AA\ as -3.87 V, referenced to the average potential in the bulk-like liquid region.</div><div>To unravel the ion-independent water effective local potential contribution to the ion hydration free energy, we estimate the 3rd cumulant term as -0.22 V from simulations totally over 6 ns, a time-scale inaccessible for AIMD calculations. </div>

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