dft study of the alkali metal influence on structure and ... no... · physics, computational...

InternationalJournalofNanoelectronicsandMaterialsVolume 11, No. 1, Jan 2018 [1-14]

DFTStudyoftheAlkaliMetalInfluenceonStructureandOpticalPropertiesofB12Nanocluster

FatemehTahmaszadeh1andHamidRezaShamlouei1,*

1DepartmentofChemistry,LorestanUniversity,KhorramAbad,Iran

Received14Feb2017;Revised6June2017;Accepted17July2017

ABSTRACT

Boronwithelectrondeficiencyhasthetendencyinauto‐combiningtoformpolyhedralstructures.The icosahedral formofB12 is thestructuralblockofboronclusterswhichundergoexothermicdimerization reaction. Itwas found that the annular shapeofB12wasmorestableincomparisonwithicosahedralB12.StructuralandopticalpropertiesoftheicosahedralformandannularshapeofB12weremodifiedbyalkalimetalatomsontheirsurfaceanditwasdemonstratedthatthereactionofalkalimetalatomswithIS‐B12isexothermicduetoitsinstability.Additionallythealkalimetalhasgreatereffectontheoptical properties of icosahedral form of B12 nanocluster. As the result, the higherpolarizabilitywasobtainedforK@IS‐B12nanocluster(269.2and399.2a.u.formonoanddi K atom respectively). The modification in first hyperpolarizability for mono‐alkalimetalatomsonIS‐B12surfacewasmoreconsiderablethandi‐alkalimetalatom.Ontheother hand, di‐alkali metal atom has slight effect on first hyperpolarizability. Themaximum first hyperpolarizability obtained for mono K atom attached to IS‐B12nanocluster(about22500a.u.).Keywords: Icosahedral B12, NLO, first hyperpolarizability, alkali metal, PACS’s No:42.65.−k,42.70.Nq,42.70.Mp

1. INTRODUCTIONCompounds with high nonlinear optical properties have great potentials in the fields ofoptoelectronicandphotonicdevices,especiallythegenerationofopticalharmonics.Thesegreatapplications have attracted scientists to investigate thematerialwith high non‐linear optical(NLO)properties[1‐7].Inscienceandtechnology,therearemanyeffectiveagentsforenhancingthe NLO properties in original molecule such as electron donor and recipient groups,establishmentofᴨelectron,anddopingatom[8‐11].Alkalimetalattachment[12‐13],transitionmetaldoping [14]andalkalimetalsuperoxideadsorption [15‐16]onnanoclustersareamongthefactorsresponsibleforhighNLOproperties.AfterexplorationofcarbonnanotubesbyIijima[17] and observation of the carbon nanotubes unique properties [18‐20], scientists begin tostudy the new nano‐scale material. Among the nano‐scale materials, the cages of inorganiccompoundhadspecialpropertieswhichwassynthetizedanddetected.Forinstance,theboronnitrideclusters,haveuniqueproperties.Oneofthepropertiesistheauto‐combiningwithitselfto form polyhedral structureswhich is one of themost interesting properties of boronwithelectron deficiency. The polyhedral form is known as Icosahedron formwhere twelve atomsoccupy twelve vertices. While their dimensions of 5.1Å are considerably larger than singleatoms,theB12polyhedrongroupsactassingleunitstoformthreedimensionalboronclusters[21]. So it is clear that the icosahedron form of B12 play an unquestionable role in bulk *Correspondingauthor:PhysicalChemistryGroup,ChemistryDepartment,LorestanUniversity,KhorramAbad,Iran.Telfax:+98‐6633120618.Emailaddress:[email protected]

FatemehTahmaszadehandHamidRezaShamlouei/DFTStudyoftheAlkaliMetalInfluence…

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propertiesofboron.Electrondeficiencyof thismoleculemakes it suitable toundergovariousreactionswithotheratoms.For instance,boroncancombineswithsomerareearthelementssuch as Lu, Y, Yb to form LuB12, YB12 and YbB12 respectively [22]. Additionally, boron cancombinewithaluminiumandcarbontoformAlB12[23]andB12C3[21]respectively.Inaddition,boron is alsousedashigh‐dose ion implantationofdopantatoms into silicon [24‐25]. In thisresearch, theB12structurewasemployedtostudy itspropertiesandtheeffectofalkalimetaldoping on B12 structure and optical properties by using the density functional theory (DFT)method.DFT is among themost extensiveandusefulmethodsavailable in condensed‐matterphysics,computationalphysics,andcomputationalchemistry.Inthistheory,thepropertiesofamany‐electron system can be determined by usingfunction of electron density. When takentheexchangeandcorrelationinteractions into consideration, the DFT method has advantagefromtheHartree–Fockmethod.2. COMPUTATIONALDETAILS

Theoptimizedgeometricalstructuresofannular formofB12(RS‐B12), icosahedronformofB12(IS‐B12) and the combination of annular form and icosahedron formwith alkalimetal atomswere calculated using density functional methods at B3LYP/6‐311+G(d) level of theory. Thenature of the stationary points was proven using the frequency analysis at the samecomputational level.The frequencyanalysiswasperformedtocalculate theenthalpyofGibbsfreeenergy.Thespin‐unrestrictedapproachwasappliedtodescribethegeometryoptimization,electronicstructureandNLOpropertiesofallstructures.ThenewdensityfunctionalCoulomb‐attenuated hybrid exchange‐correlation functional (CAM‐B3LYP) which is suitable to predictthe molecular NLO properties of a large system [26‐27] was employed to calculate thepolarizability and first hyperpolarizability of nanoclusters. All calculations were performedusingGaussian09package[28].The highest occupiedmolecular orbital energy and the lowest unoccupiedmolecular orbitalenergy(HOMO‐LUMO)gap(Eg)valuesareusedinordertoexploretheelectronicpropertiesoftheconsideredclusters.TheHOMO‐LUMOgaphasthefollowingoperationalequation:

Eg=εH‐εL (1)

whereεHandεListhehighestoccupiedmolecularorbital(HOMO)andthelowestunoccupiedmolecularorbital(LUMO)energiesrespectively.Variationoftheenergywiththeelectricfieldstrengthisgivenby:

⟨ ⟩ (2)In presence of the electric field (ε), the energy of molecule (E) can be considered as TaylorexpansionrelativetoitsenergyintheabsenceofthefieldE(0):

0! !

⋯(3)

wherethesubscript0indicatesthatthederivativeisevaluatedatε=0.WhentheEq.(3)mixedtoEq.(2),thefollowingresultisobtained.

⟨ ⟩ ⋯(4)


3

Theexpectationvalueof theelectricdipolemoment inthepresenceof theelectric field is thesumofapermanentdipolemomentandthecontributionsinducedbythefield.Therefore,theexpectation value of the electric dipole moment in the presence of the electric field can bewrittenasshowninEq.(5):

⟨ ⟩ ⋯ (5)

Iftheexpectationvalueofμinalldirectionswasrequested,thefollowingequationcanbeused.

⟨ ⟩ . ⋯ (6)

where μ is the μx, μy, and μz, α and are the matrix elements of polarizability and firsthyperpolarizability.Thesimplestpolarizability(α),characterizestheabilityofanelectricfieldtodistort theelectronicdistributionof amolecule related to linearopticalproperties.Higherorderpolarizabilities(hyperpolarizabilitiesβ,γ,etc.)describethenonlinearresponseofatomsandmoleculesrelatedtoawiderangeofphenomenafromnonlinearoptics[29‐31].Usingtwo‐levelmodel[32],therelationbetweenhyperpolarizibilityandothertimedependentpropertieswereobtainedthroughthefollowingrelation:

β∝f∆µ/∆E3 (7)

where∆E represent the transitionenergy, f represent theoscillator strength, and∆μ indicatethedifferenceinthedipolemomentsbetweenthegroundstateandthecrucialexcitedstate.Inthis model, is proportional to ∆E3 hence ∆E is the decisive factor in the firsthyperpolarizability[33].Duetothedependencyofthefirsthyperpolarizabilityongroundandexcitedstateproperties,thetime‐dependentdensityfunctionaltheory(TD‐DFT)calculationsatCAM‐B3LYP/6‐31+G(d)level of theorywere done to obtain the excitation energy and the differences of their dipolemomentsbetweenthegroundstateandexcitedstateaswellastheoscillatorstrengthf.3. RESULTSANDDISCUSSION3.1OptimizedstructureThe chemical bond between the icosahedron‐B12 plays an important role in the chemistry ofboroncompounds.Therefore,inordertounderstandthenatureof,chemicalbondbetweentheicosahedron‐B12, firstly, the structure of IS‐B12 was optimized at B3LYP/6‐31+G(d) level oftheory. Then the dimerization of IS‐B12 and annular shape of B12 was investigated. TheoptimizedstructureofIS‐B12,dimerofB12andRS‐B12werecalculatedandillustratedinFigure1(a),Figure1(b)andFigure1(c)respectively.InFigure1, two typesofB‐Bbondexist.R1 is locatedbetween twoboronatoms insideeachmonomerandR2is locatedbetweentwoboronatomsintwoadjacentmonomers.InFigure1(a),theB12consistsoficosahedralstructurewhichisapolyhedronformwithtwentytriangularfaces. Asmentioned in the introduction, the B12 polyhedron groups act as single unitwhichhavehightendencytoplayasmonomerformingthreedimensionalboronclusters.


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a b C

Figure1.Optimizedstructuresof(a)icosahedralB12,(b)dimerofIS‐B12and(c)annularB12(RS‐B12)at

B3LYP/6‐311+G

InTable1,thestructuralinformation(R1andR2values)aswellastheenergeticpropertiesofIS‐B12anditsdimerwasreported.TheR1intheIS‐B12is1.705whichisslightlydifferentfromB‐BobtainedbyYamauchiet.al(1.75)[34].AstheresultofcombiningtwoB12molecules,theR1bondlengthslightlyshortenedandthedimerizationproducedanexothermicreaction.TheB‐Bbondlengththatoccurredbetweentwoadjacentmonomersis1.687whichisinagreementwithpreviousdata(1.71)[34].

Table1Thestructuralinformation,energeticpropertiesofIS‐B12anditsdimer

R1 R2 E(kCal.mol‐1) H(kCal.mol‐1) G(kCal.mol‐1)

IS‐B12 1.705 ‐1179.26 ‐1162.41 ‐1064.63Dimer 1.692 1.687 ‐2450.56 ‐2413.88 ‐2202.27

Incomparisonto icosahedralstructure, theB12mayexist inannularshape(ring‐shapeorRS)which consists of two optimized six member rings. The optimized structure of RS‐B12 wasdepicted inFigure1 (c).TheenergeticpropertiesofRS‐B12were calculated. Interestingly theRS‐B12 is more stable than IS‐B12 which 295 kJ.mol‐1 energy difference found between twoconfigurations.Lowstabilityof the IS‐B12maybethereasonof its tendencytocombinewithitself.Additionally,itseemsthattheelectrondeficiencycharacteristicofIS‐B12makeitsuitabletoreactwithalkalimetals.Thereby,investigationwascontinuedwiththeplacementoflithium,sodium and potassium atoms on the surfaces the two configurations of B12. The optimizedstructureswerecalculated.Thestructuresoftheadsorbedmonoanddi‐alkalimetalatomsontheIS‐B12surfaceweredepictedinFigure2.

Li@IS‐B12 Na@IS‐B12 K@IS‐B12

Li2@IS‐B12 Na2@IS‐B12 K2@IS‐B12

BLiNaK

Figure2.Optimizedstructuresofmonoanddi‐alkalimetaladsorbedonIS‐B12nanoclustersatB3LYP/6‐311+G(d)leveloftheory

A1

A2

A3

R1


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AsillustratedinFigure2,fourB‐BandB‐X(inwhichXcorrespondtoalkalimetalatoms)bondsexist.InTable2,thevaluesofA1toA4bondlengthsforeachcomplexofalkalimetalatomswithIS‐B12nanoclusterwerecompared.Inthepresenceoflithiumatoms,theA1bondlength(whichistheB‐Bbondexistbetweentwoboronatomsfarfromalkalimetalatoms)wasshortenedbutinNaandKcase,theA1increases.TheA2bondlengthwhichoccursbetweentwoBnearthealkalimetalatomsincreasesinpresenceofalkalimetalatoms.Theinteractionlengthofalkalimetal atoms depend on their atomic radius and the smallest bond was obtained for lithiumatomandlargestforpotassiumatom.Theinteractionlengthsarealmostconstantifthenumberof alkali metal atoms increase. Finally the A4 which is the distance of two boron atoms inadjacent fivememberringswasshortened inexistenceofalkalimetalatoms. Incontinuation,thealkalimetalwereattachedontheRS‐B12andtheirstructureswereoptimizedanddepictedinFigure3.

Table2ThestructuralinformationofIS‐B12withdifferentcomplexesofalkalimetal

Li@RS‐B12 Na@RS‐B12 K@RS‐B12

Li2@RS‐B12 Na2@RS‐B12 K2@RS‐B12

BLiNaK Figure3.Optimizedstructuresofmonoanddi‐alkalimetalatomadsorbedonannularB12atB3LYP/6‐

311+G(d)leveloftheoryThe informationof optimized structureofmonoanddi‐alkalimetal atoms complex ofRS‐B12wasgatheredinTable3.

A4A3A2A1Typeofstructure

1.704‐ ‐1.736IS‐B12

1.6982.1471.7761.667 Li@IS‐B12

1.6632.4611.8121.793Na@IS‐B12

1.6593.0011.8441.850K@IS‐B12

1.6472.1531.820‐Li2@IS‐B12

1.6472.461 1.810‐Na2@IS‐B12

1.6632.9181.876‐K2@IS‐B12

D3

D2

D4

D1


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Table3ThestructuralpropertiesofRS‐B12anddifferentcomplexesofalkalimetalwithit

AsshowninTable3,aftercombinationofRS‐B12withalkalimetalatoms,theD1andD2bondswereshortenedandthestrengthofthemincreasesinpresenceofalkalimetalatoms.WhentwoalkalimetalatomsattachedtoRS‐B12theB‐Bbondlengthwasfurthershortened.SimilartoIS‐B12, distance of alkali metal atoms to B atoms depend on the size of alkali metal atom andshorterdistancewasseenfor lithiumatom.Whenthenumberof lithiumatomsincreases, theinteractionlengthbetweentheatomsdecreases.Ontheotherhand,thedistancebetweentwoBatomsinadjacentring(D4)increasesinpresenceofalkalimetalatoms.3.2Electronicproperties

For calculation theelectronicpropertiesofmolecule, theHOMOandLUMOorbitals for IS‐B12andRS‐B12 complexwith alkalimetal atomswere calculated and the energy gap valueswereobtained. In Figure 4 the HOMO and LUMO orbitals for all considered clusters and thecorrespondingdensityofstate(DOS)wasdemonstrated.

IS‐B12 Li@IS‐B12 Na@IS‐B12 K@IS‐B12

RS‐B12 RS@RS‐B12 Na@RS‐B12 K@RS‐B12

Figure4.TheHOMO,LOMOorbitalsforallclustersandcorrespondingDOSforthem

D4D3D2D1Typeofstructure

1.695‐ ‐ 1.624RS‐B12

1.7222.244 1.6171.611Li@RS‐B12

1.7252.663 1.6171.610 Na@RS‐B12)

1.7273.070 1.616 1.609 K@RS‐B12

1.7432.225 1.605‐Li2@RS‐B12

1.7502.641 1.605‐Na2@RS‐B12

1.7573.034 1.603‐ K2@RS‐B12


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TheresultsoftheEHOMO,ELUMO,Eganddipolemoment()foreachclusterswereshowninTable4.ForthepristineRS‐B12andIS‐B12,theobtainedHOMOenergiesare‐6.12and‐4.6respectivelywhereas,theLUMOenergiesforRS‐B12andIS‐B12are‐3.14and‐3.6respectively.TheEgforRS‐B12 and IS‐B12 are 2.98 eV and, 1 eV respectively. The lower Eg of IS‐B12 demonstrates theinstabilityinitsstructure.Contradictory,theinfluenceofalkalimetalonEgmaybetheresultofdifference between the Eg of two pristine B12 configurations. The HOMO and LUMO energieswere increased by alkali atom presence. However, increase in ELUMO for M@IS‐B12 is moreconsiderableandsotheEgincreases.Ontheotherhand,forRS‐B12,increasinginEHOMOismoreconsiderable and so the Eg decreases. The calculated EHOMO, ELUMO, Eg and electrical dipolemomentsforthepristineB12andM@B12intwoconfigurationsareshowninTable4.

Table4TheresultsofEHOMO,ELUMO,EgandfortwoconfigurationsofB12andcomplexofalkalimetal

atomswiththem

EgELUMOEHOMOTypeofstructure

0.002.98 ‐3.14 ‐6.12RS‐B12

3.93782.22 ‐2.29‐4.51Li@RS‐B12

7.01702.11 ‐2‐4.11 Na@RS‐B12

9.8132.07 ‐1.76 ‐3.83 K@RS‐B12

0.00042.55 ‐1.98‐4.53Li2@RS‐B12

0.00022.36 ‐1.46‐3.82Na2@RS‐B12

0.00092.28 ‐1.06‐3.34 K2@RS‐B12

0.001 ‐3.6‐4.6IS‐B12

7.74162.1‐2.47‐4.57 Li@IS‐B12

8.07341.64‐2.68‐4.32Na@IS‐B12

11.33401.86‐2.61‐4.47K@IS‐B12

0.00151.82‐1.95‐3.77Li2@IS‐B12

0.00121.74 ‐2.08‐3.82Na2@IS‐B12

0.00141.32‐3.04‐1.72K2@IS‐B12 ToindicatetheorientationofthecomplexofalkalimetalatomwithtwoconfigurationofB12inelectricfield,themolecularelectrostaticpotentialsurfaceofthemwereplottedanddepictedinFigure5.InFigure5,thelocationsofthevariousmostpositiveandmostnegativeregionswereshown bymolecular electrostatic potential surface. In IS‐B12 andRS‐B12, the electron densitymainlyconcentratedovertwoheadofthemolecules.Thedistributionofchargeissymmetricalandtheclustershavenoorientationinelectricfields.Inthecomplexofalkalimetalatomwiththese clusters, the head of alkali metal complex have positive charge and other head hasnegativechargewhichorientedtowardthepositivepole.Additionallythepositivechargeofthealkalimetalheadsillustratesthechargetransferfromalkalimetaltonanocluster.


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HOMO LUMO RS‐B12

HOMO LUMO Li@RS‐B12

HOMO LUMO Na@RS‐B12

HOMO LUMO K@RS‐B12

HOMO LUMO Li2@RS‐B12

Eg=2.98 eV

Eg=2.22 eV

Eg=2.11 eV

Eg=2.07 eV

Eg=2.55 eV


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HOMO LUMO Na2@RS‐B12

HOMO LUMO K2@RS‐B12

HOMO LUMO IS‐B12

HOMO LUMO Li@IS‐B12

HOMO LUMO Na@IS‐B12

Eg=2.36 eV

Eg=2.28 eV

Eg=1.00 eV

Eg=2.01 eV

Eg=1.64 eV


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HOMO LUMO K@IS‐B12

HOMO LUMO Li2@IS‐B12

HOMO LUMO Na2@IS‐B12

HOMO LUMO K2@IS‐B12

Figure5.Molecularelectrostaticpotentialsurfaceofthecomplexofalkalimetalatomwithtwo

configurationofB12.3.3Opticalproperties

Thepolarizability(α),andfirstorderstatichyperpolarizability(β0)ofpristineB12andM@B12intwo configurations are calculated using DFT theory at CAM‐B3LYP/6‐ 31+G (d,p) level. Thevalues of polarizability (α), and first order static hyperpolarizability (β0) for mentionedstructuresarepresentedinTable5.

Eg=1.86 eV

Eg=1.82 eV

Eg=1.74 eV

Eg=1.32 eV


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Table5CalculatedresultsofαandfortwoconfigurationsofB12anddifferentcomplexwithalkalimetalatoms

f(a.u.)oαTypeofstructure

0.00030.31148.6RS‐B12

0.04751877.6180.2Li@RS‐B12

0.05285909.1194.3Na@RS‐B12

0.05447159.3202.6K@RS‐B12

0.09821.5202.6Li2@RS‐B12

0.23100.9243.3Na2@RS‐B12

0.20084.4269.2K2@RS‐B12

0.03200.015192.0IS‐B12

0.01075741.7204.9Li@IS‐B12

0.001011333.9210.7 Na@IS‐B12

0.005422491.2230.1K@IS‐B12

0.13311.09231.2Li2@IS‐B12

0.44461.8299.4Na2@IS‐B12

0.58890.036392.2K2@IS‐B12 AccordingtodatapresentedinTable5,thepolarizabilityofIS‐B12andRS‐B12is192.0and148.6respectively.ThelargerpolarizabilityinIS‐B12isprobablyduetoitshighervolume.AlkalimetalatomsattachmentonbothconfigurationsofB12 increase itpolarizabilitywhich ispredictableandtheorderofincreaseinpolarizabilityisK>Na>Li.ThefirsthyperpolarizabilityforB12inthetwoconfigurations(IS‐B12andRS‐B12)isnearzero.Consequently,theattachmentofalkalimetal remarkably increased the polarization. Increase in β0 as consequence of alkali metalpresenceismuchconsiderableforIS‐B12configuration.Similartopolarizability,theorderofβ0improvementisK>Na>Li.Table5proventhatitwaspredictablethatattachmentoftwoalkaliatoms on nanocluster have no improvement effect on the hyperpolarizability (due to highdegree of symmetry). In addition, themaximum of first hyperpolarizabilitywas obtained forK@IS‐B12(22491.2a.u.)3.4TD‐DFTThe two‐level model [27,28] was used to explain the increase in hyperpolarizability of B12nanoclusters.Thismodelisconsideredas:

0 ∝

∆ .

∆ (8)

where∆E, f0and∆µare the transitionenergy,oscillatorstrength,anddifference in thedipolemoments between the ground state and the crucial excited state with the largest oscillatorstrength.According toEq. (3) theβ0value is reverselyproportional to the thirdpowerof thetransitionenergy,soitisthenoteworthyfactorinthefirsthyperpolarizability.Time‐dependentdensity functional theory(TD‐DFT)calculationsatCAM‐B3LYP/6‐31+G(d) levelof theorywasused to obtain transition excited state properties. The properties such as excitation energiesΔE(eV),xcitationwavelengthλ(nm)ndoscillatorstrengths f(a.u)ofallconfigurations listed inTable6.


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Table6Theexcitationenergy∆E,wavelengthandoscillatorstrengthffortwoconfigurationsofB12nanocluster

Typeofstructure ∆E(eV) λ(nm) f(a.u.)RS‐B12 2.8738 431.43 0.0003Li@RS‐B12 2.1721 570.79 0.0475Na@RS‐B12 2.0711 598.63 0.0528K@RS‐B12 2.0474 605.58 0.0544Li2@RS‐B12 2.6880 461.26 0.0982Na2@RS‐B12 2.3241 533.47 0.2310K2@RS‐B12 2.0924 592.55 0.2008IS‐B12 1.1727 1057.26 0.0320Li@IS‐B12 1.2472 994.09 0.0107Na@IS‐B12 1.1845 1046.75 0.0010K@IS‐B12 1.0891 1138.42 0.0054Li2@IS‐B12 2.1930 565.37 0.1331Na2@IS‐B12 2.2450 552.26 0.4446K2@IS‐B12 1.7241 719.12 0.5889

Results in Table 6 is in agreement with Eq. (3). For similar configurations, the firsthyperpolarizability has the same behaviour as the reverse transition energy. The firsthyperpolarizibility (β0) for the same structures with one adsorbed alkali metal atoms wereplottedasfunctionoftransitionenergy(∆E)andillustratedinFigure6.In Figure 6, it is clear that the excitation energy inversely related to the values of firsthyperpolarizibility. Small changes in transitionenergy can causedrasticmodifications in firsthyperpolarizability. Among theM@IS‐B12complexes, the K@IS‐B12 has the smallest transitionenergy and has large value of first hyperpolarizability (22491.2 a.u). Similarly, among theM@RS‐B12 complexes, the K@RS‐B12 has minimum transition energy andmaximum value offirsthyperpolarizability(7159.3a.u.).

Figure6.Thelogarithmof0asfunctionoftransitionstateoftwoconfigurationsofB12withalkalimetalatoms

3

3.2

3.4

3.6

3.8

4

4.2

4.4

1 1.2 1.4 1.6 1.8 2 2.2 2.4

Log()

E (eV)

M@B12 (2)


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4. CONCLUSION

InthisresearchtheicosahedralformofB12whichisthestructuralblockofboronclusterswasemployed.AnexothermicdimerizationreactionwasobservedbetweentwoIS‐B12nanoclusters.Additionally,itwasshownthattheannularformofRS‐B12hasmorestability.Then,theeffectofalkalimetalatomonstructureandopticalpropertiesoftwoconfigurationofB12wereexplored.ItwasshownthatthenetchargetransfertakeplacefromalkalimetalatomtoB12nanocluster.Additionally,itwasdiscoveredthatthealkalimetalhassuperioreffectontheicosahedralformofB12nanocluster.Forinstance,thehigherpolarizabilitywasobtainedforicosahedralinwhichtheKatomattachedtoIS‐B12nanocluster(269.2and399.2a.u. formonoanddiKatom).ThefirsthyperpolarizabilityforIS‐B12wasmodifiedbyadsorptionofmono‐alkalimetalatomsonitssurface.Thedi‐alkalimetalatomontheotherhandhaslittleeffectonfirsthyperpolarizability.The maximum first hyperpolarizability obtained for mono K atom attached to IS‐B12nanocluster. According to two‐level model, slight reduction in transition energy significantlymodifies the first hyperpolarizability which explains the alkali metal effect on firsthyperpolarizability.REFERENCES[1] Kleinman,D.A,Phys.Rev.126(1962)1977[2] Pandey.V,Mehta.N,Tripathi.S.K,Kumar.A,J.Optelectron.Adv.M.7(2005)2641[3] Zhong,R.L,Xu.H.L,Muhammad.S,Zhang.J,Su.Z.M,J.Mater.Chem.22(2012)2196[4] Tu.C,Yu.G,Yang.G,Zhao.X,Chen.W,Li.S,Huang.X,Chem.Chem.Phys.16(2014)1597[5] Zhou.F,He.J.H,Liu.Q,Gu.P.Y,Li.H,Xu.G.Q,Lu.J,M,J.Mater.Chem,100(2014)6850[6] Hatua.K,Nandi.P.K,J.Phys.Chem.A.117(2013)12581[7] Muhammad.S,Xu.H,Su.Z,J.Phys.Chem.A.115(2011)923[8] Marder. S. R, Gorman. C. B, Meyers. F, Perry. J. W, Bourhill. G, Brédas. J. L, Pierce. B.

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dft study of the alkali metal influence on structure and ... no... · physics, computational...

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