Electronically coarse grained waterAndrew Jones Flaviu Cipcigan Vlad Sokhan Jason Crain Glenn Martyna

Problem

Challenge

Intermolecular interactions depend on environment

Develop simplest water model with electronic responses

Problem

1. Quantum Drude Oscillator (QDO)Light negative particle tethered harmonically to heavy positive, oppositely charged nucleus

Free parameters

reduced mass

spring constant

charge

Polarisabilities

Dispersion coefficients

dipole

dipole–dipole

dipole–quadrupole

…

1. Quantum Drude Oscillator (QDO)

2. The responses of QDOs are realistic

CH4 H2O

He Ne Ar Kr Xe

H Li K Rb Cs

1.5

1.5

1.5

0.5

0.5

0.5

1

1

1

Polarisation

Dispersion

1.5

1.5

1.5

0.5

0.5

0.5

1

1

1

CH4

BH3 NH

3 H2O

He Ne Ar Kr Xe

H Li K Rb Cs

2. The responses of QDOs are realistic

3. QDO waterFrame: ground state charge distribution

+ 0.605 e

- 1.21 e

0.2667 Å0.957

2 ÅO

H

M

H 104.52º

Frame: ground state charge distribution

= 0.3656 amu

= 0.6287

= -1.1973 e

3. QDO waterQDO: responses

3. QDO waterShort range: empirical repulsion

4. Liquid QDO water

Radial distribution function

r / Å2345 67

g OO(r

)

0.0

0.5

1.0

1.5

2.0

2.5Skinner et al. (exp).Exp. (Soper)QDO, N = 300

4. Liquid QDO water

Radial distribution function Vapour pressure

exp: 43.91 kJ/mol

r / Å2345 67

g OO(r

)

0.0

0.5

1.0

1.5

2.0

2.5Skinner et al. (exp).Exp. (Soper)QDO, N = 300

46 ± 2 kJ / mol

4. Liquid QDO water

Radial distribution function Vapour pressure

exp: 43.91 kJ/mol

r / Å2345 67

g OO(r

)

0.0

0.5

1.0

1.5

2.0

2.5Skinner et al. (exp).Exp. (Soper)QDO, N = 300

46 ± 2 kJ / mol

Dielectric constant

exp: 7879 ± 2

4. Liquid QDO water

Radial distribution function Vapour pressure

exp: 43.91 kJ/mol

r / Å2345 67

g OO(r

)

0.0

0.5

1.0

1.5

2.0

2.5Skinner et al. (exp).Exp. (Soper)QDO, N = 300

46 ± 2 kJ / mol

Dielectric constant

exp: 7879 ± 2

Surface tension

exp: 71.73 mN / m72.6 ± 1 mN / m

5. Liquid–vapour interface of QDO water

5. Liquid–vapour interface of QDO water

5. Liquid–vapour interface of QDO water

loss & gain of electronic chargein bulk

5. Liquid–vapour interface of QDO water

loss & gain of electronic chargeat surface

5. Liquid–vapour interface of QDO water

loss & gain of electronic chargelast surface layer

6. Conclusions

simple, but with a complex electronic structure

transferability may be good, under investigation

QDO water

model of the isolated molecule, condensed properties emerge naturally

A. Jones, Quantum drude oscillators for accurate many-body intermolec-ular forces, PhD thesis, The University of Edinburgh

A. Jones, F. Cipcigan, V. Sokhan, J. Crain, G. Martyna, Electronically coarse grained model for water, PRL 110, 227801 (2013)

Electronically coarse grained waterAndrew Jones Flaviu Cipcigan Vlad Sokhan Jason Crain Glenn Martyna