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MONTE CARLO SIMULATION OF MOLECULES AND IONS IN LIQUID WATER MICHAEL YUDISTIRA PATUWO NATIONAL UNIVERSITY OF SINGAPORE 2011 MONTE CARLO SIMULATION OF MOLECULES AND IONS IN LIQUID WATER MICHAEL YUDISTIRA PATUWO (B.Sc.(Hons), NUS) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN SCIENCE DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2011 Abstract herivtion of retion free energy of hemil proesses in queous environments n e ided y the knowledge of hydrtion free energyF wonte grlo simulE tion n e done in onjuntion with the thermodynmi perturtion methodD y mens of fennett9s eptne rtioD in order to otin the free energyF he solute moleule ws morphed9 from nonEinterting ghost9 moleule inside ox ontining sQGsR wter moleules under the periodi oundry onditions to its full potentil funtionsD y sujeting the two endpoint systems nd interE medite systems with softEore soluteEsolvent intertion potentils to seprte wg simultionsF ell wg simultions were performed using homegrown portrnWH proE grm tht llowed hoie of solvent models nd ustom intertion funtionsD nd ws wellEtilored for morphing oriented worksF e good del of ttention ws put on the potentil funtions used for soluteEsolvent intertionF hile empiril funtions were usedD they re lrgely onsistent with estlished theoretil rguments nd onstrutsF Acknowledgments pirst nd foremostD s would like to thnk my supervisor nd mentorD essoF rofF yn F eF fettensD for his guidne nd ounsel in oth my undergrdute nd grdute yersD for nurturing my interest in the (eld of physil nd omputtionl hemistryD nd for eing onstnt soure of inspirtion for meF s lso thnk every leturer s9ve hd the honour to e tught y in the pst seven yersD who hd rought me where s m right nowD hrF edrin wF vee for mking me n quintne to the (eld of quntum hemistry nd for his demi guidneD nd essoF rofF pn i ip nd essoF rofF ung rwy ghunD who were the exminers for the quli(tion exm for my hFhF ndidtureD for giving me wkeEup slp nd put me k on trkF ithout ll of you s would not hve loved ghemistry the wy s right nowD nd s would not hve ome this frF wnyD mny thnks to my junior nd friend ve ri enh yoD whose resourefulE ness nd determintion were invlule to meY qod less her in her future endevE oursF wy undergrdute nd grdute friends who hd een here in the sme l together with me through thik nd thinX urishnnD glrD ndrD rui tiD emeliD it would hve een so dull without ll of youF s would lso extend my thnks to vow ti inD my quintne sine seondry shool nd gret friend throughout my yers in x F feing hemistry mjor would not hve een the sme without youF s lso thnk everyone who hd helped me during my hFhF ndidture yers in vrious wysD wiss uriwti finte 9d for her help in nonEdemi mttersD essoF rofF horsten ohlnd for his ides nd inititive onerning the grdute mttersD ung hing qene nd the giD for llowing me to use their mhines to signi(nt prt of my workD nd everyone else who hd helped me in wys tht s my not e wre of or hve forgottenF s m honoured to e student of x D nd s m forever grteful for the grdute reserh sholrship tht s ws o'eredF ithout itD it would hve een impossile for me to my grdute studies in ingporeF hnk you my prentsD for enourging me in the demi pth tht s hve hosenD nd te'y nd risy for lwys elieving in their ig rotherF wmi nd piD s love you so muhF hnk you fennyD for stiking with me fter we9ve moved out of x residentil hllsF hnk you iu unD for sitting those physis letures with meD uennyD my hll friend nd gming mteD ll the ool people who were under eiex sholrship with me k in the dysD my xtg lssmtesD my friends in xt ghorle nd esonne old nd youngF hese four yers would hve een so di'erent without your friendshipF vooking kD s not nd will never regret the deision of oming to ingpore nd doing my hFhF work in x F he tresured memories will forever sty with meD whtever the future my eF Contents Summary List of Tables List of Figures List of Symbols The Dynamics of Molecular Systems IFI IFP IFQ IFR sntermoleulr pores"e remle F F F F F F F F F F F F F F iletrostti intertions F F F F F F F F F F F F F F F F F F F F IFPFI wultipole moments nd moleule in n eletri (eld IFPFP iletrostti intertions etween moleules F F F F F IFPFQ histriuted multipoles F F F F F F F F F F F F F F F F F xonEeletrostti intertions F F F F F F F F F F F F F F F F F IFQFI sndution energy F F F F F F F F F F F F F F F F F F F F IFQFP hispersion energy F F F F F F F F F F F F F F F F F F F F IFQFQ ixhngeErepulsion energy F F F F F F F F F F F F F F F reliminry glultions F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F gomputer imultion wethods F F F F PFIFI wetropolis elgorithm F F F F F PFIFP eriodi foundry gonditions F PFIFQ iwld ummtion wethod F F PFIFR NpT ensemle F F F F F F F F F PFIFS pree inergy F F F F F F F F F F F PFIFT eeptne tio wethod F F F PFIFU worphing F F F F F F F F F F F F PFIFV oftEore potentil F F F F F F F he MC rogrm F F F F F F F F F F F F PFPFI qenerl )ow of the progrm F F PFPFP reprtive steps F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F SS F TP F TT F UH F UV F VI F VR F VW F WR F WW F IHR F IHT xitrogen F F F F wethne F F F F wethnol F F F gron dioxide futne F F F F F fenzene F F F F ithnoi id F ithnmide F F gonlusion F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F Molecular Monte Carlo Simulation PFI PFP Simulation of Neutral Molecules QFI QFP QFQ QFR QFS QFT QFU QFV QFW i iv vii ix F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F I U V IQ IW PS PT QI QW RH 55 111 III IPI IPV IQU IRH IRT ISP ISV ITQ Simulation of Zwitterions RFI RFP RFQ RFR qenerl omments F F F elnine F F F F F F F F F esprgine F F F F F F F xeurminidse inhiitors RFRFI nmivir F F F F RFRFP ermivir F F F F Conclusion Bibliography A Spherical harmonics B Multipole moments F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F 167 ITU ITV IUS IVQ IVS IVW 193 197 209 213 fFI ypertors F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F PIQ fFP qeometry onversions for multipole moments F F F F F F F F F F F F F PIR fFQ ghnging the origin of multipole moments F F F F F F F F F F F F F F F PIS C Interaction functions D Program and Auxiliary Files 219 223 hFI MC F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F PPQ hFP Bennett_1000 F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F PPT hFQ shell F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F F PPU 214 Appendix B Multipole moments ytopoles ˆ Oαβγ = qi i rα rβ rγ − |r|2 (rα δβγ + rβ δγα + rγ δαβ ) 2 @fFRA sf αD β D nd γ re distintX ˆ Oααα = 3 rα − |r|2 rα 2 qi i ˆ Oααβ = qi i ˆ Oαβγ = rα rβ − |r|2 rβ 2 qi i rα rβ rγ B.2 Geometry conversions for multipole moments Table B.1: Conversions between spherical and Cartesian geometry up to rank pheril to grtesin grtesin to spheril ˆ M00 =q ˆ ˆ M10 = pz ˆ ˆ M11c = px ˆ ˆ M11s = py ˆ ˆ M20 ˆ = Ozz ontinuedFFF B.3 Changing the origin of multipole moments 215 le fFI !ontinued pheril to grtesin grtesin to spheril √ ˆ M21c = √ ˆ Ozx ˆ Ozx = ˆ M21s = √ ˆ Ozy ˆ Ozy = ˆ M22c = √ ˆ Oxx ˆ = − M20 + ˆ M22s = √ ˆ Oyy ˆ = − M20 − ˆ Oxy = ˆ ˆ Oxx − Oyy ˆ Oxy ˆ M30 ˆ M21c √ ˆ M21s √ ˆ M22c √ ˆ M22c √ ˆ M22s ˆ = Ozzz ˆ M31c = ˆ Ozzx ˆ Ozzx = ˆ M31c ˆ M31s = ˆ Ozzy ˆ Ozzy = ˆ M31s ˆ M32c = ˆ M32s =2 ˆ Oxyz ˆ Oxyz = ˆ 12 M32s ˆ M33c = √1 10 ˆ ˆ Oxxx − 3Oxyy ˆ Ozxx = ˆ 12 M32c ˆ M33s = √1 10 ˆ ˆ 3Oxxy − Oyyy ˆ Ozyy =− ˆ Oxxx = ˆ M33c − ˆ M31c ˆ Oxxy = ˆ M33s − ˆ 24 M31s ˆ Oxyy = ˆ M33c − ˆ 24 M31c ˆ Oyyy = ˆ M33s − ˆ M31s ˆ ˆ Ozxx − Ozyy ˆ − M30 ˆ 12 M32c ˆ − M30 ˆ ˆ (k) sn generlD Mk0 = Mzz z B.3 Changing the origin of multipole moments he stndrd ddition theorem for regulr spheril hrmonis is written s suh PPX l l1 l2 δl1 +l2 ,l (−1)l+m Rlm (a + b) = l1 ,l2 m1 =−l1 m2 =−l2 (2l + 1)! (2l1 )!(2l2 )! 216 Appendix B Multipole moments l2 l l1 × Rl1 m1 (a)Rl2 m2 (b) m1 m2 −m where the igner QEj oe0ient @fFSA l1 l2 l m1 m2 −m is relted to gleshEqordn oe0ients s followsX l2 l l1 l −l −m l1 m1 , l2 m2 |lm = (−1) √ 2l + m1 m2 m @fFTA e see tht the term δl1 +l2 ,l rosses out ny term where l1 + l2 = lD nd hene we n rewrite the ove eqution s suhX l1 l Rlm (a + b) = l1 =0 m1 =−l1 l+m l−m l1 + m1 l1 − m1 pinllyD if we tke position vetor Rl1 m1 (a)Rl−l1 ,m−m1 (b) a to e the initil origin @fFUA O of the multipole moments nd c = −b s the position vetor of the new origin C @refer to (gure fFIAD we hveX L l C MLM = l=0 m=−l L+M L−M l+m l−m O Mlm RL−l,M −m (−c) @fFVA nfortuntelyD there is no onise wy to express the new multipole terms in its rel O formD nd t the losest it would require the omplex forms of the unshifted Mlm nywyF egrdlessD this trnsformtion is useful in ses suh s where distriuted multipoles re used in order to desrie the eletri (eld of moleuleD nd whenever it mkes more sense to de(ne the origin t the new site @suh s t the entre of hrge of the moleuleD or t spei( tomFA B.3 Changing the origin of multipole moments 217 Figure B.1: Change of origin for multipole moments expansion A new origin can be placed at the site where a set of multipole moments are dened, such as at the centre of an atom, if distributed multipoles were to be used instead of a central one 219 Appendix C Interaction functions sn le gFI is list of intertion funtions T ab in spheril tensor formD suh tht the eletrostti rmiltonin is given yX ˆ ˆ Mla κ1 Mlb κ2 Tlab ,l2 κ2 1κ HEL = @gFIA l1 ,l2 κ1 κ2 his tle is tken from The Theory of Intermolecular Forces y eF tF tone IPUD pges PQQEPRHD nd is inluded here solely for illustrtion purposesD s the sme intertion funtions re used with ritil importne in the progrm MC y F F eF fettensF xo ltnt opying is intended ! s pologise in dvne for ny o'ene used y the inlusion of this mterilF he nottions used in the tle re derived from the reltive orienttions of the intertion moleules ording to their lol xesD s illustrted in pigure gFIF king ea , ea , ea s the unit vetors de(ning the lol xes of site nd similrly x y z eb , eb , eb for site D then cαβ = ea · eb D where α nd β my reple xD y D or z F elsoD x y z α β a tking eab s the unit vetor in the diretion of r(b) − r(a)D then rα = ea · eab nd α b rβ = −eb · eab F β st should lso e noted tht the multipole terms with susripts IHD IID nd IIsD re respetively equivlent to IzD IxD nd Iy @refer to le fFIAF 220 Appendix C Interaction functions Figure C.1: Demonstration of local axes systems of interacting molecules for formulating interaction functions Not shown in the gure is the global axes system, which is the axes system of the laboratory Table C.1: List of interaction functions up to l , l l1 κ1 l2 κ2 4πε0 Tlab ,l2 κ2 1κ 00 00 R−1 1α 00 R−2 × a rα 20 00 R−3 × a2 (3rz 21c 00 R−3 × 21s 00 R−3 × 22c 00 R−3 × 22s 00 R−3 × ontinuedFFF √ − 1) a a 3rz rx √ a a 3rz ry √ a2 a2 3(rx − ry ) √ a a 3rx ry =2 221 le gFI !ontinued l1 κ1 l2 κ2 4πε0 Tlab ,l2 κ2 1κ 1α 1β R−3 × a b (3rα rβ + cαβ ) 20 1β R−4 × a2 b (15rz rβ 21c 1β R−4 × 21s 1β R−4 × 22c 1β R−4 × 22s 1β R−4 × a a a a b 3(ry czβ + cyβ rz + 5rz ry rβ ) √ a2 a2 b a a 3(5(rx − ry )rβ + 2rx cxβ − 2ry cyβ ) √ a a b a a 3(5rx ry rβ + rx cyβ + ry cxβ ) 20 20 R−5 × a2 b (35rz rz 20 21c R−5 × R−5 × 2czx czz ) √ a2 b b b b a b a b 3(35rz rz ry −5rz ry +10rz ry czz +10rz rz czy + R−5 × 2czy czz ) √ a2 b2 b2 a b a b 3((35rz −5)(rx −ry )+20rz rx czx +rz ry czy + R−5 × 2c2 − 2c2 ) zy zx √ a2 b b a b a b 3((35rz − 5)rx ry + 10rz rx czy + rz ry czx + 20 20 20 21s 22c 22s √ √ a b + 6rz czβ − 3rβ ) a a a a b 3(rx czβ + cxβ rz + 5rz rx rβ ) √ a b a b − 5rz − 5rz + 20rz rz czz + 2c2 + 1) zz a b b b b a b a b 3(35rz rz rx −5rz rx +10rz rx czz +10rz rz czx + 2czx czy ) 21c 21c R−5 × a a b b a b a b a b (35rz rx rz rx + 5rx rx czz + 5rx rz czx + 5rz rx cxz + a b 5rz rz cxx + czz cxx + czx cxz ) 21c 21s R−5 × a a b b a b a b a b (35rz rx rz ry + 5rx ry czz + 5rx rz czy + 5rz ry cxz + a b 5rz rz cxy + czz cxy + czy cxz ) 21c 22c R−5 × a a b2 (35rz rx (rx b a b a b − ry ) + 10rx rx czx − 10rx ry czy + a b a b 10rz rx cxx − 10rz ry cxy + 2cxx czx − 2cxy czy ) ontinuedFFF 222 Appendix C Interaction functions le gFI !ontinued l1 κ1 l2 κ2 4πε0 Tlab ,l2 κ2 1κ 21c 22s R−5 × a a b b a b a b a b (35rz rx rx ry + 5rx rx czy + 5rx ry czx + 5rz rx cxy + a b 5rz ry cxx + czy cxx + czx cxy ) 21s 21s R−5 × a a b b a b a b a b (35rz ry rz ry + 5ry ry czz + 5ry rz czy + 5rz ry cyz + a b 5rz rz cyy + czz cyy + czy cyz ) 21s 22c R−5 × a a b2 (35rz ry (rx b a b a b − ry ) + 10ry rx czx − 10ry ry czy + a b a b 10rz rx cyx − 5rz ry cyy + 2czx cyx − 2czy cyy ) 21s 22s R−5 × a a b b a b a b a b (35rz ry rx ry + 5ry rx czy + 5ry ry czx + 5rz rx cyy + a b 5rz ry cyx + czy cyx + czx cyy ) 22c 22c R−5 × a2 (35(rx b a − ry )(rx 2 a b b − ry ) + 20rx rx cxx − a b a b a b 20rx ry cxy −20ry rx cyx +20ry ry cyy +2c2 −2c2 − xx xy 2c2 + 2c2 ) yy yx 22c 22s R−5 × b b a2 (35rx ry (rx a a b a b − ry ) + 10rx rx cxy + 10rx ry cxx − a b a b 10ry rx cyy − 10ry ry cyx + 2cxx cxy − 2cyx cyy ) 22s 22s R−5 × a a b b a b a b a b (35rx ry rx ry + 5rx rx cyy + 5rx ry cyx + 5ry rx cxy + a b 5ry ry cxx + cxx cyy + cxy cyx ) 223 Appendix D Program and Auxiliary Files et the k of this thesis is gh ontining the (les tht were used extensively during the ourse of this reserhD rrnged in diretoriesF sn this setion short desriptions of the forementioned (les re givenF D.1 MC euthorsX fettensD F F eFY veD rF eFY nd tuwoD wF F sn this diretory re the soure odes @in portrnUU nd portrnWHAD exeutE lesD smple input nd summry output (les for the simultion progrm MC version 1.4.01.MF he output dt (le ontining soluteEsolvent energy during morphing run @to ompute solvtion free energy using the fennett eeptne tioA is too lrge to e inluded in this listingD nd hene is omitted out from the ghF ed the mnul MC_Manual.docx for thorough desription of (les of this typeF pile nme hesription alanine4.in mple input (leF ontinuedFFF 224 Appendix D Program and Auxiliary Files le hFI !ontinued pile nme hesription alanine4.out mple output (le ontining summry of simE ultion runD generted from alanine4.in nd iC_4EL000.datF constants.f90 oure (leF wodule ontins physil onstnts nd onversion ftorsF electroEn.f90 oure (leF wodule lultes eletrostti energy eE tween ny two moleules using entrl or distriuted multipolesF ewald.f90 oure (leF wodule sets up kEvetors nd lultes the relD reiprolD selfD intrmoleulrD nd vuum energy terms of the iwld9s summtion funtion for eletrostti energyF globals.f90 oure (leF wodule delres most glol vriles nd rrysF input.f90 oure (leD written y toneD eFtF @PHHSAF kge omplements io.f90 y filitting reding of input (lesF iC_4EL000.dat mple ompnying input (leF gontin initil onE (gurtion dt for solvent moleulesF io.f90 oure (leF wodule reds input nd writes formtted output (lesF Makefile wke(leF o e used with pgf95 portrn ompilerF MC_1404M ixeutleF his (le exeutes the progrm MCD version 1.4.01.MF ontinuedFFF D.1 225 MC le hFI !ontinued pile nme hesription mc.f90 opElevel soure (leF gontins the min ulk of the progrmF MC_Manual.docx wirosoft ord PHHU doument (leF gontins the mnul of the progrmF multi.f90 oure (leF wodule delres roots of integerD rrys for multipole momentsD hndles their onversion eE tween grtesin nd spheril oordinte systemsD nd heks for their trelessnessF numRec.f portrnUU soure (leF kge ontins numeril reipesD suh s the erf nd erf funtionsF parameters.f90 oure (leF wodule delres severl ontrol vrilesD their mximum sizesD nd de(nes tom nmesF random.f90 oure (leD written y wlrenD xFwF@IWWPAF wodE ule ontins funtion dprand() tht genertes rnE dom numer etween H nd IF eed is stored in random.dataF timing.f90 oure (leD written y toneD eFtF @PHHSAF wodule trks pu time spent during jo runF tip4p.f90 oure (leF wodule de(nes prmeters for sQ nd sR wter models nd ontins suroutines ssoiE ted with solvent energyF ontinuedFFF 226 Appendix D Program and Auxiliary Files le hFI !ontinued pile nme hesription vector.f90 oure (leF wodule ontins suroutines for vetor normlistionD ross produtD nd genertion of rotE tion mtrixF Table D.1: Files in MC directory, listed alphabetically Unless specied otherwise, all source les are compatible with the Fortran90 language (.f90 extension) D.2 Bennett_1000 euthorsX fettensD F F eFD modi(ed y tuwoD wF F sn this diretory re the soure odes @in portrnWHAD exeutlesD nd smE ple output (les for the progrm Bennett_1000D designed to lulte the estimte hnge in free energy using one of the output (les generted y MC during morE phing run s inputF es mentioned eforeD this (le is not ville in the gh s it is too lrgeF pile nme hesription Bennett_1000 ixeutleF his (le exeutes the progrm Bennett_1000D whih reds soluteEsolvent intertion energy dt every IDHHH timesteps to estimte the solE vtion free energyF ontinuedFFF D.3 227 shell le hFP !ontinued pile nme hesription bennett_1000.f90 opElevel soure (leF gontins the min ulk of the progrmF constants.f90 ee le hFIF EL_ala4.out mple output (le for morphing of eletrostti potenE til with λEL = 0.25 @systems vi to xAF globals.f90 (Obsolete) input.f90 ee le hFIF io.f90 oure (leF wodule reds input nd writes formtted ee le hFIF output (lesF LJ_ala4.out mple output (le for morphing of nonEeletrostti potentil with λLJ = 0.25 @systems i to vAF Makefile wke(leF o e used with pgf95 portrn ompilerF parameters.f90 ee le hFIF timing.f90 ee le hFIF Table D.2: Files in Bennett_1000 directory, listed alphabetically D.3 shell euthorX tuwoD wF F sn this diretory re the soure odes @in portrnWHAD exeutlesD smple input nd output (les for the progrm shellD designed to nlyse the rdil distriution of solvent moleules using the on(gurtion dump (les generted y MC s inputF 228 Appendix D Program and Auxiliary Files pile nme hesription dmpxxxx.gjf mple input (lesF gontins oordintes of ll solvent moleules in the simultion oxF Shell ixeutleF his (le exeutes the progrm ShellD whih lultes the density of spei( toms round requested oordinte t regulr distnesF shell.f90 oure (leF shell.in mple input ontrol (leF yptions for the progrm re spei(ed hereF Table D.3: Files in Shell directory, listed alphabetically ... MONTE CARLO SIMULATION OF MOLECULES AND IONS IN LIQUID WATER MICHAEL YUDISTIRA PATUWO (B.Sc.(Hons), NUS) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN SCIENCE DEPARTMENT OF. .. Regardless, magnetic interactions due to both electronic and nuclear spin are generally too small to be considered in the context of intermolecular forces, and they are often safely and reasonably... the sum of the pirwise intertionsF his isD of ourseD mjor onern tht often plgues simultions of very lrge ssemliesF gorretions of suh sle would onsume lrge mount of omputtionl