Liquid-Liquid Equilibria of C8H18 O3 and H2O by Molecular Dynamics

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Charlene Powell
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1 Liquid-Liquid Equilibria of C8H18 O3 and H2O by Molecular Dynamics Thermodynamics and Energy Technology, University of Paderborn Computational Chemical Engineering (CoChE) Fraunhofer SCAI V r = K b l l 0 K 0 bonds 2 angles 1 V n [ 1 cos n ] torsions 2 N 1 N j =1 i = j 1 { [ ] i, j ij r ij 12 ij 2 r ij 6 qi q j 4 0 r ij }

softmatter problems through state-of-the-art quantum mechanics, atomistic, and mesco-scale research, modeling,

2 Synopsis of SCAI and the CoChE Group SCAI: ~90 Employees + 40 PhD Students - highly interdisciplinary CoChE: founded in 2008: ~5 senior staff (PhDs) - active with students Mission Statement: To computationally solves industrially relevant softmatter problems through state-of-the-art quantum mechanics, atomistic, and mesco-scale research, modeling, mathematics, and algorithm development. High-resolution bridging of ideas and experimental observables. Schloß Birlinghoven Campus

3 Multiscale Modeling......is A Means to an End. GROW ms2

Customized Force Field Generation = E H ~50 atoms 1 2 2 V r = K b l l 0 K 0 bonds 2 angles 1 V n [ 1 cos n ] torsions 2 N atom { [ ] ab f scnb a b ab r ab 12 ab 2 r ab 6 f scee qa qb

4 Customized Force Field Generation = E H ~50 atoms V r = K b l l 0 K 0 bonds 2 angles 1 V n [ 1 cos n ] torsions 2 N atom { [ ] ab f scnb a b ab r ab 12 ab 2 r ab 6 f scee qa qb 4 0 r ab } Force Fields are... fundamental component of molecular mechanics based research extremely important difficult to optimize requires specialized knowledge & is time consuming

5 Wolf2 Pack Workflow for Force Field Optimization Package Scientific workflows: a) save time by automating certain tasks, b) force-field development becomes quasi-deterministic and reproducible, thereby reducing human error, c) enable tasks to be executed in a distributed environment, d) can accommodate ideas, algorithmic changes, and updates that take place within each step e) accelerate and transform the scientific & analysis process.

6 Initial Parameters Gradient-based opt (Steepest Descent Newton Raphson Conjugate Gradient Trust Region) Current Parameters Calc. Physical Properties via MD Compare to Target Properties Good Final Parameters GROW Bad Comparison is done by evaluating the loss function d F y = i =1 T T F y =0 f exp i,t sim i,t exp i,t F f y 2

7 Time-Line for IFPSC June 16th October 15th weeks 7 8 Intermolecular Parameterization for DME a) Literature Search b) Experimental Design c) QM Target Data d) Intramolecular Parameterization Intramolecular DPGDME Production MDs Parameterization a) 353 K b) 333 K c) 323 K DME + H2O MD d) 283 K At 333 K TIP4P water Writing dimethoxyethane DPGDME + H2O System Size Adjustments and MDs at 353 K dipropylene glycol dimethyl ether

8 Methodology Initial Parameters TraPPE (UA Force Field) J Phys Chem B 108, 2004, QM Target Data HF/6-31G(d)//HF/6-31G(d) for geometries B3LYP/6-31++G(2d,2p)//HF/6-31G(d) for energies 7 Bond Parameters J Comp Chem 29, 2008, Angle Parameters DME, DPGDME, and Training Molecules 21 Torsion Parameters > 990 QM calculations 2 Improper Torsions TIP4P/2005 Water (All-atom Force Field) J Chem Phys 123, 2005, Model Sizes System 1: 47,503 Waters and 6,134 DGPDMEs System 2: 30,000 Waters and 875 DGPDMEs MD Simulations 5 ns Equilibrium & 5 ns each Temperature Software GAMESS and GROMACS J Comp Chem 14, 1993, 1347 J Chem Theory Comput 4, 2008, 435

Intra-molecular (Training Molecules, Wolf2 Pack) 4) Inter-molecular (DME, GROW) Data

9 DPGDME Molecular Isomers 3 Structural Isomers 11 Spatial Isomers Parameterization Steps: 1) Intra-molecular (Training Molecules, Wolf2 Pack) 2) Inter-molecular (DME, GROW) 3) Intra-molecular (Training Molecules, Wolf2 Pack) 4) Inter-molecular (DME, GROW) Data Collection: System 1 Use data obtained from organic phase GROW System 2 Use data obtained from water phase

10 1,2-Dimethoxyethane (DME) Results Quantum Mechanics vs. Molecular Mechanics Density for Neat DME torsion Target Data (QM orexperiment) TraPPE New Intra- and Inter-molecular TraPPE + New Intra-molecular Partial Densities for 333 K

11 System 2 DPGDME/H2O Density for Neat DPGDME System 1 DPGDME/H2O Dipropylene glycol dimethyl ether (DPGDME) Results

12 Molar Fraction of DPGDME in H2O Molar Fraction of DPGDME in DPGDME System 1 Exp. System 2 Exp. Mass Percent of DPGDME Experiment vs. Predicted

13 The Team Karl Kirschner Thorsten Köddermann Thomas Brandes Anton Schüller Marco Huelsmann Antje Wolf Dirk Reith Astrid Maa Jadran Vrabec Ferag Selim Highly interdisciplinary team with broad competences for many types of problems Physical Engineers & Mathematicians & Chemists & Software Engineers

14 GROW ms2 Thank you for your attention. High-resolution bridging of ideas and experimental observables.

Example questions for Molecular modelling (Level 4) Dr. Adrian Mulholland

Example questions for Molecular modelling (Level 4) Dr. Adrian Mulholland 1) Question. Two methods which are widely used for the optimization of molecular geometies are the Steepest descents and Newton-Raphson