ReactionPathwaysthrough
MolecularDynamics(MD)of
Methanol
andHydroxylcationon
InterstellarWatericesurfaces
DavidArias-OlivaresPh.D.(c)MolecularPhysical Chemistry,UNAB,Chile
NataliaInostroza-PinoPh.D.HeadofQuantumAstrochemistry Group,UAC,Chile
July6th,2016.Campinas,SP.
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
WhyGrain-Surfacechemistry?
KeyFormationMechanisms
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
ClassicalMolecularDynamics
Since atoms are approximated as discrete particles, interactions of smaller particles
cannot be correctly modeled with classical MD.
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
E (Kcal/mol)
-1007.2027
-1008.0091
Which partofallicemantle
isthemostinteresting?
-1012.8097
-2098.5289
-2103.1274
-2115.644
Initial
Final
E (Kcal/mol)
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
-2100.590
-2101.397
-2101.455
-2113.622
Which themoststable
spatialconfiguration?
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
• Wefoundtheoptimalcoordinates
configurationasfollow:
Surface (Ice Mantle)
Molecule
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
WhyQuantum
MolecularDynamics?
Makingandbreakingchemicalbonds,
noncovalentreactionintermediates,
andprotonorelectrontunneling all
cannotbesimulatedwithClassical
MolecularDynamics
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
QuantumMolecularDynamics
• Quantummolecular
dynamicsmethodsexist
forsimulationsthatcanbe
moreelectronically
realistic,butatmuch
greatercomputational
cost.
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
QuantumMolecularDynamics
• Whatifwemove
fromgas-phase
reactiontograinsurfacereaction?
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
HoveroverIcemantles
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
NextTheoreticalWork
• Scaleuptoabiggerclusteranduseitasatargetfor
theHO- projectile.Aquantumdynamicsdescription.
• Exploreasmuchaswecan,differentwaystoimpact
thegrainsurfaceanddescribethechemicalreaction
onthedustgrain.
• Oncedesigned,it isimportanttousedifferent
projectilestounderstanddifferentreactionpathways.
ReactionPathwaythroughClassicalMolecularDynamics(MD)ofMethanolandHydroxylcationon
InterstellarWatericesurfaces.
ThankYou!