Quantum Mechanical Prediction of the Existence

of Rare Gas-bound Species

Katheryn Shi1, Brent Wilson2, Angela K. Wilson3

1 TAMS, University of North Texas2 Department of Chemistry, University of North Texas

3 Faculty Mentor, Department of Chemistry, University of North Texas

IntroductionComputational chemistry: combines math, chemistry,

and computer science to solve chemical problems

Computational chemistry may be used where laboratory work is impracticalDangerous compoundsMolecules difficult to isolate

Trying to solve the Schrödinger equation and obtain properties (e.g. optimal geometries, vibrational frequencies, charge distributions, dissociation energies, etc.)

IntroductionHΨ=EΨ – Schrödinger Equation

H – Hamiltonian OperatorΨ – Wave functionE – Eigenvalue (energy)

ˆ ˆ ˆ ˆˆ ˆe n ne nn eeH T T V V V= + + + +

IntroductionBefore the 1960’s, rare gases (noble

gases)were considered inert.

XePtF6 was synthesized by Neil Bartlett in 1962*, opening a new area of exploration

More recently, organic rare gas compounds have been prepared (HXeCCH†, HXeCC†, HKrCCH, etc.)

*Bartlett, N. "Xenon hexafluoroplatinate Xe+[PtF6]?" Proceedings of the Chemical Society of London. 1962: 218.

†Khriachtchev, Leonid, Hanna Tanskanen, Jan Lundell, Mika Pettersson, Harri Kiljunen, and Markku Räsänen. "Fluorine-Free Organoxenon Chemistry:  HXeCCH, HXeCC, and HXeCCXeH." J. Am. Chem. Soc.. 125 (16) (2003): [4696–4697 ]. 

Research Goal

Discover new rare-gas compounds with useful properties

Method versus Basis Set

Hartree-FockDFT

MP2 CISDCCSD

QCISD(T)CCSD(T)

MP4 Full CI

“Exact”solution to

H=E

Bas

is S

et S

ize

Method

DZ

TZ

QZ

5Z

6Z

∞

MethodologyB3LYP

Type of density functionalTotal energy expressed as a function of electron

densityNot wave function based

Second-order Møller-Plesset perturbation theory (MP2) Begins with Hartree Fock calculation and adds in

energy to account for electron correlation

Methodology

CCSD(T)Includes higher excitations and recovers

more correlation energy than MP2

Methodology

Basis setsSet of functions representing atomic orbitalsUsed to describe the character of the electrons

in atoms or molecules

Correlation consistent basis setsaug-cc-pVnZ (n = D, T, Q)Designed to systematically recover correlation

energy with increase in size

ProcedureGeometry

OptimizationsTry to find a

minimum on the potential energy (PE) surface

Frequency CalculationsMake sure there are

no imaginary frequencies to confirm PE minimum

Procedure

Start with B3LYPLess computationally expensiveFalse positives

Check molecules that converged using B3LYP with more sophisticated methods, such as MP2 and CCSD(T)

Molecules Tested HArN HKrN ArCAr ArCCAr ArCCCAr FArKr FKrAr FKrN HArCCCN HArKr HArO HeCCHe HKrAr HKrCCCN

HKrKr HKrNe HKrS HKrSe KrCCCKr KrCCKr HArBr HArCl HCCKrN NKrCCCN FArCCCN FKrCCCN FArCCArCCArF FKrCCKrCCCKrCCK

rF

BrKrCCKrBr BrKrGeGeKrBr ClArCArCCCArCAr

Cl ClArCCArCl ClArCCCArCl ClKrPPKrCl ClNeCCCNeCl HCCArN NArCCCN HArP ClArCCArCCArCl ClArSiSiArCl FArN FKrCKrCCCKrCKrF

Molecules Tested FKrKrCCCKrKrF FNeCCCNeF HArCCCCN HArCCN HCArN HCCCArN HCCCKrN HCKrN KrCKr NArCCCCN NKrCCCCN ClKrCCKrCl ClNeCCNeCCNeCl ClNeCCNeCl

HeCHe HKrCCCCCN HKrCCCCN HKrCCKrH HKrCCN HKrO Br(CKr)6

HArAs HKrP Kr(CH)6

Kr(CO)6

Kr2SO4

Kr4SO4

ClNeCNeCCCNeCNeCl

FArCCArF FArCCCCCN FKrCCCCCN FKrCCKrCCKrCCKrF FKrCCKrCCKrF FKrS FKrSiCKrF FKrSiSiKrF FNeCCNeCCNeF FNeCCNeF FNeCNeCCCNeCNe

F HArCCCCCN HeCCCHe

Potential New Rare Gas Molecules

ResultsHArN HKrN

Method Basis Set H–Ar Ar–N H–Kr Kr–N

B3LYP aug-cc-pVnZ

n = D 1.283 2.140 1.426 2.163n = T 1.578 2.220 1.419 2.135n = Q 1.566 2.208 1.664 2.240

MP2 aug-cc-pVnZ

n = D 1.271 2.196 1.409 2.215n = T 1.259 2.108 1.399 2.131n = Q 1.258 2.087 1.400 2.108

CCSD(T) aug-cc-pVnZ

n = D 1.297 2.261 1.452 2.294n = T 1.272 2.185 1.425 2.220n = Q 1.270 2.165 1.425 2.202

Results

Conclusions

HArN and HKrN were predicted to be stableFrequency calculations indicated the

geometries were minimum energy pointsBond lengths converged with increasing basis

set sizeBond length analysis indicated covalent

properties

Contain nitrogen - unique

Interest in noble gas molecules due to laser action354nm laser discovered using XeF in 1975

Applications

ApplicationsHArN and HKrN were predicted to be stable

MedicineAnti-tumor agentsLaser eye surgery

IndustryExcimer lasers for semiconductor

manufacturing

AcknowledgementsProf. Angela WilsonBrent WilsonDr. Mike

DrummondDr. Jamal UddinDr. Wanyi JiangThe Wilson Group

National Science Foundation

Department of Education (CASCaM)

National Center for Supercomputing Applications

University of North TexasFaculty Research GrantAcademic Computing

Services for UNT Research Cluster

Texas Academy of Mathematics and Science