Thermo-molecular orientation effects in fluids of dipolar dumbbells
File(s)dumbbells_Sep1_nomarkup.pdf (408.81 KB)
Accepted version
Author(s)
Daub, CD
Astrand, P-O
Bresme, F
Type
Journal Article
Abstract
We use molecular dynamics simulations in applied thermal gradients to study thermomolecular orientation (TMO) of size-asymmetric dipolar dumbbells with different molecular dipole moments. We find that the direction of the TMO is the same as in apolar dumbbells of the same size, i.e. the smaller atom in the dumbbell tends to orient towards the colder temperature. The ratio of the electrical polarization to the magnitude of the thermal gradient does not vary much with the magnitude of the molecular dipole moment. We also investigate a novel second order TMO that persists even in size-symmetric dipolar dumbbells where molecules have a slight tendency to orient perpendicular to the gradient except very close to the hot region, where (anti-)parallel orientations are preferred. Finally, we investigate rotational correlation functions and characteristic rotational times in these systems in an attempt to model possible spectroscopic signatures of TMO in experiments. Although we cannot detect any difference in integrated rotational times between equilibrium simulations and simulations in a thermal gradient, more careful modelling of the anisotropic rotational dynamics in the thermal gradient may be more successful.
Date Issued
2014-10-28
Date Acceptance
2014-09-02
Citation
Physical Chemistry Chemical Physics, 2014, 16 (40), pp.22097-22106
ISSN
1463-9084
Publisher
Royal Society of Chemistry
Start Page
22097
End Page
22106
Journal / Book Title
Physical Chemistry Chemical Physics
Volume
16
Issue
40
Copyright Statement
© The Royal Society of Chemistry 2014
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Physics, Atomic, Molecular & Chemical
Chemistry
Physics
PRIMITIVE MODEL ELECTROLYTES
CANONICAL ENSEMBLE
PHASE-EQUILIBRIA
HEAT-TRANSFER
DYNAMICS
SIMULATION
WATER
SIZE
POLARIZATION
CRITICALITY
Publication Status
Published