Post on 19-Jun-2020
By:ShaunPachecoHarveyMuddCollege
Advisor:Dr.PatrickSchellingUniversityofCentralFlorida
SilicateMinerals Compoundbearingsiliconanion Foundinuppermantle(90%ofcrust)
Olivine(Mg,Fe)2SiO4 Asteroids Weathersquickly
http://en.wikipedia.org/wiki/File:Peridot2.jpg
SiliconTetrahedron 3differentoxygensites
O1furthestoxygen O2closestoxygen O3equidistant
O2
O3
O3
O1 Si
StructureofOlivineM2SiO4
Orthorombic ForsteriteMg2SiO4
FayaliteFe2SiO4 Twometalsites FeprefersM1siteM1
M1
M2
M2
Op8calProper8es DependentonMagnesium‐Ironconcentration
Iron’svalenceelectronsleadstosmallerbandgap
Fayalite
http://en.wikipedia.org/wiki/File:Fayalite_crystal_group_‐_Ochtendung,_Eifel,_Germany.jpg
http://en.wikipedia.org/wiki/File:Forsterite_on_Sanidine_‐_Ochtendung,_Eifel,_Germany.jpg
Forsterite
DensityFunc8onalTheory Ground‐stateenergyuniquefunctionaloftheelectrondensity
Findsetofwavefunctionsthatminimizeenergyfunctional.
!
"!2
2me
+Veff (" r )
#
$ %
&
' ( )* (" r ) = E*)* (
" r )
!
n! r ( ) = "#
$ ! r ( )"#
! r ( )
#
occ
%
PointDefects SchottkyDefect–defectconsistingofananionandcationvacancyinfinitelyfarapart
SchottkyDefectClusters–defectconsistingofananionandcationvacancy
http://en.wikipedia.org/wiki/File:Naclschottkydefect.svg
SpaceWeathering Createspointdefects Micrometeoriteimpacts Solar‐windsputtering Interactionswithcosmicrays
FiniteSizeEffects
SmallSystemMg1O3
LargerSystemMg1O3
M2
M2
M1
M2
M2 M1
SchoFkyDefectResults Forsterite:
Mg2‐O3defectlowestenergy3.65eV Mg2‐O2defecthighestenergy7.52eV
Differentresultsthanempiricalpotentials
OxygenVacancy Forsterite:O2sitemostenergeticallyfavorable8.45eV
Fayalite:O3sitemostenergeticallyfavorable7.90eV
M1
M1
M2
M2
FutureWork Biggercellsizes Furtherstudyopticalproperties Propertiesofolivineasfunctionofironcontent Surfaces
Ques8ons?
References Payne,etal.“Iterativeminimizationtechniquesforabinitiototal‐energycalculations:
moleculardynamicsandconjugategradients.”Oct1992. http://en.wikipedia.org/wiki/File:Peridot2.jpg http://en.wikipedia.org/wiki/File:Forsterite_on_Sanidine_‐
_Ochtendung,_Eifel,_Germany.jpg http://en.wikipedia.org/wiki/File:Fayalite_crystal_group_‐
_Ochtendung,_Eifel,_Germany.jpg http://en.wikipedia.org/wiki/File:Naclschottkydefect.svg