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Sotiris Xantheas

Chemical Physics & Analysis
Laboratory Fellow
Pacific Northwest National Laboratory
PO Box 999
MSIN: K1-83
Richland, WA 99352


Dr. Sotiris Xantheas is known in the chemical physics scientific community for his research in intermolecular interactions in aqueous ionic clusters and the use of ab-initio electronic structure calculations to elucidate their structural and spectral features. His research has ranged from the computation of potential energy surfaces for various chemical reactions using correlated wavefunctions to the elucidation of reaction paths governing carbene ring opening processes and the location and characterization of intersections of potential energy surfaces of the same symmetry in polyatomic systems. He has recently utilized the results of high-level electronic structure calculations to parametrize a family of ab-initio based interaction potentials for water and used those potentials to simulate the macroscopic properties of liquid water and ice.

Research Interests

  • Structures, vibrational spectra, electric properties and energetics of aqueous clusters
  • Quantitative description of many-body non-additive effects in clusters and condensed phase environments
  • Development of interaction potentials based on first principles to study water, ice and aqueous solvation of ions.

Education and Credentials

  • Postdoctoral fellow, Pacific Northwest National Laboratory, USA
  • Ph.D., Chemistry, Iowa State University, Ames, Iowa, USA
  • Diploma, Chemical Engineering, National Polytechnic University of Athens, Greece

Affiliations and Professional Service

  • American Association for the Advancement of Science (AAAS) Fellow (2010)
  • American Physical Society (APS) Fellow (2005)
  • Institute for Advanced Study, Technical University of Munich at Garching, Visiting Fellow (2012-present)
  • Japan Society for the Promotion of Science (JSPS) Fellow (2011)
  • Elected member, Executive committee, American Chemical Society (ACS), Division of Physical Chemistry (2009-2012)
  • American Chemical Society (ACS) member
  • Institute for Electronic Structure and Laser, Foundation for Research and Technology, Crete, Greece, adjunct member (1996-)
  • Director, NATO Advanced Study Institute on "Recent Theoretical and Experimental Advances in Hydrogen Bonded Clusters," in 1997

Awards and Recognitions

  • Director's Award for Exceptional Scientific Achievement, Pacific Northwest National Laboratory (2013)
  • Advisory Editorial Board, Chemical Physics Letters (2013-2015)
  • Editorial Advisory Board, Journal of Physical Chemistry (2012-2014)
  • Elected Member, Council of Fellows, Pacific Northwest National Laboratory (2009-present)
  • Fellow, American Association for the Advancement of Science
  • Alexander von Humboldt Foundation Award, 2009
  • "Friedrich Wilhelm Bessel" award from the Alexander von Humboldt Foundation in Bonn, Germany, 2003
  • Director's Award for Outstanding Performance, Pacific Northwest National Laboratory (2003)
  • Presented numerous invited talks at academic institutions, research centers and international meetings
  • Fellow, American Physical Society
  • Laboratory Fellow at Pacific Northwest National Laboratory (2004-present)

PNNL Publications


  • Brorsen KR, SY Willow, SS Xantheas, and MS Gordon. 2015. "The melting temperature of liquid water with the effective fragment potential." Journal of Physical Chemistry Letters 6(18):3555-3559.  doi:10.1021/acs.jpclett.5b01702
  • Ebata T, R Kusaka, and SS Xantheas. 2015. "Laser Spectroscopic and Theoretical Studies of the Structures and Encapsulation Motifs of Functional Molecules." In Proceedings of the International Conference of Computational Methods in Sciences and Engineering (ICCMSE 2010), October 3-8, 2010, Kos, Greece. AIP Conference Proceedings, vol. 1642, ed. TE Simos and G Maroulis, p. 51.  American Institute of Physics, Melville, NY.  doi:10.1063/1.4906630
  • Fournier JA, CT Wolke, MA Johnson, TT Odbadrakh, KD Jordan, SM Kathmann, and SS Xantheas. 2015. "Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H+(H2O)n=2 - 28 Clusters." Journal of Physical Chemistry A 119(36):9425-9440.  doi:10.1021/acs.jpca.5b04355
  • Imoto S, SS Xantheas, and S Saito. 2015. "Ultrafast dynamics of liquid water: Energy relaxation and transfer processes of the OH stretch and the HOH bend." Journal of Physical Chemistry B 119(34):11068-11078.  doi:10.1021/acs.jpcb.5b02589
  • Miliordos E, and SS Xantheas. 2015. "An accurate and efficient computational protocol for obtaining the Complete Basis Set limits of the binding energies of water clusters at the MP2 and CCSD(T) levels of theory: Application to (H2O)m, m=2-6, 8, 11, 16 and 17." Journal of Chemical Physics 142(23):234303.  doi:10.1063/1.4922262
  • Miliordos E, and SS Xantheas. 2015. "Ground and excited states of the [Fe(H2O)6]2+ and [Fe(H2O)6]3+ clusters: Insight into the electronic structure of the [Fe(H2O)6]2+ - [Fe(H2O)6]3+ complex." Journal of Chemical Theory and Computation 11(4):1549-1563.  doi:10.1021/ct501143c
  • Miliordos E, and SS Xantheas. 2015. "On the validity of the basis set superposition error and complete basis set limit extrapolations for the binding energy of the formic acid dimer." Journal of Chemical Physics 142(9):094311.  doi:10.1063/1.4913766
  • Werhahn JC, E Miliordos, and SS Xantheas. 2015. "A new variation of the Buckingham exponential-6 potential with a tunable, singularity-free short-range repulsion and an adjustable long-range attraction." Chemical Physics Letters 619:133-138.  doi:10.1016/j.cplett.2014.11.051


  • Miliordos E, and SS Xantheas. 2014. "Elucidating the mechanism behind the stabilization of multi-charged metal cations in water: A case study of the electronic states of microhydrated Mg2+, Ca2+ and Al3+"." Physical Chemistry Chemical Physics. PCCP 16(15):6886-6892.  doi:10.1039/C3CP53636J
  • Miliordos E, and SS Xantheas. 2014. "On the bonding nature of ozone (O3) and its sulfur-substituted analogues SO2, OS2 and S3: Correlation between their biradical character and molecular properties." Journal of the American Chemical Society 136(7):2808-2817.  doi:10.1021/ja410726u
  • Miliordos E, and SS Xantheas. 2014. "Unimolecular and hydrolysis channels for the detachment of water from microsolvated alkaline earth dication (Mg2+, Ca2+, Sr2+, Ba2+) clusters." Theoretical Chemistry Accounts 133(4):Article No. 1450.  doi:10.1007/s00214-014-1450-4
  • Miliordos E, E Apra, and SS Xantheas. 2014. "Benchmark Theoretical Study of the p-p Binding Energy in the Benzene Dimer." Journal of Physical Chemistry A 118(35):7568-7578.  doi:10.1021/jp5024235
  • Pradzynski CC, CW Dierking, F Zurheide, RM Forck, U Buck, T Zeuch, and SS Xantheas. 2014. "Infrared detection of (H2O)20 isomers of exceptional stability: a drop-like and a face-sharing pentagonal prism cluster." Physical Chemistry Chemical Physics. PCCP 16(48):26691-26696.  doi:10.1039/c4cp03642e
  • Sahu N, SR Gadre, P Bandyopadhyay, E Miliordos, and SS Xantheas. 2014. "Low energy isomers of (H2O)25 from a hierarchical method based on Monte Carlo Temperature Basin Paving and Molecular Tailoring Approaches benchmarked by full MP2 calculations." Journal of Chemical Physics 141(16):164304.  doi:10.1063/1.4897535
  • Vasdekis AE, MJ Wilkins, JW Grate, RT Kelly, A Konopka, SS Xantheas, and MT Chang. 2014. "Solvent Immersion Imprint Lithography." Lab on a Chip 14(12):2072-2080.  doi:10.1039/C4LC00226A
  • Werhahn JC, D Akase, and SS Xantheas. 2014. "Universal scaling of potential energy functions describing intermolecular interactions. II. The halide-water and alkali metal-water interactions." Journal of Chemical Physics 141(6):064118.  doi:10.1063/1.4891820
  • Xantheas SS, and JC Werhahn. 2014. "Universal scaling of potential energy functions describing intermolecular interactions. I. Foundations and scalable forms of new generalized Mie, Lennard-Jones, Morse, and Buckingham exponential-6 potentials." Journal of Chemical Physics 141(6):064117.  doi:10.1063/1.4891819
  • Yoshida T, WA Farone, and SS Xantheas. 2014. "Isomers and conformational barriers of gas phase nicotine, nornicotine and their protonated forms ." Journal of Physical Chemistry B 118(28):8273-8285.  doi:10.1021/jp501646p


  • Doi K, E Togano, SS Xantheas, R Nakanishi, T Nagata, T Ebata, and Y Inokuchi. 2013. "Microhydration Effects on the Intermediates of the SN2 Reacation of Iodide Anion with Methyl Iodine." Angewandte Chemie International Edition 52(16):4380-4383.  doi:10.1002/anie.201207697
  • Imoto S, SS Xantheas, and S Saito. 2013. "Molecular origin of the difference in the HOH bend of the IR spectra between liquid water and ice." Journal of Chemical Physics 138(5):054506-1/8.  doi:10.1063/1.4789951
  • Imoto S, SS Xantheas, and S Saito. 2013. "Ultrafast dynamics of liquid water: Frequency fluctuations of the OH stretch and the HOH bend." Journal of Chemical Physics 139(4):Article No. 044503.  doi:10.1063/1.4813071
  • Iwata S, P Bandyopadhyay, and SS Xantheas. 2013. "Cooperative Roles of Charge Transfer and Dispersion Terms in Hydrogen-Bonded Networks of (H2O)n, n = 6, 11, and 16." Journal of Physical Chemistry A 117(30):6641-6651.  doi:10.1021/jp403837z
  • Mardirossian N, DS Lambrecht, L McCaslin, SS Xantheas, and MP Head-Gordon. 2013. "The Performance of Density Functionals for Sulfate-Water Clusters." Journal of Chemical Theory and Computation 9(3):1368-1380.  doi:10.1021/ct4000235
  • Miliordos E, and SS Xantheas. 2013. "Efficient procedure for the numerical calculation of harmonic vibrational frequencies based on internal coordinates." Journal of Physical Chemistry A 117(32):7019-7029.  doi:10.1021/jp3127576
  • Miliordos E, E Apra, and SS Xantheas. 2013. "Optimal geometries and harmonic vibrational frequencies of the global minima of water clusters (H2O)n, n=2-6, and several hexamer local minima at the CCSD(T) level of theory." Journal of Chemical Physics 139(11):114302-13.  doi:10.1063/1.4820448
  • Miliordos E, K Ruedenberg, and SS Xantheas. 2013. "Unusual Inorganic Biradicals: A Theoretical Analysis." Angewandte Chemie International Edition 52(22):5736-5739.  doi:10.1002/anie.201300654


  • He X, O Sode, SS Xantheas, and S Hirata. 2012. "Second-order many-body perturbation study of ice Ih." Journal of Chemical Physics 137(20):204505-8. 
  • Hou G, H Wen, KA Lopata, W Zheng, K Kowalski, N Govind, XB Wang, and SS Xantheas. 2012. "A Combined Gas-Phase Photoelectron Spectroscopic and Theoretical Study of Zeise's Anion and Its Bromine and Iodine Analogues." Angewandte Chemie International Edition 51(26):6356-6360.  doi:10.1002/anie.201201959
  • Lambrecht DS, L McCaslin, SS Xantheas, E Epifanovsky, and MP Head-Gordon. 2012. "Refined Energetic Ordering for Sulfate-Water (n=3-6) Clusters Using High-Level Electronic Structure Calculations." Molecular Physics 110(19-20):2513-2521.  doi:10.1080/00268976.2012.708442
  • Sams RL, SS Xantheas, and TA Blake. 2012. "Vapor Phase Infrared Spectroscopy and Ab Initio Fundamental Anharmonic Frequencies of Ammonia Borane." Journal of Physical Chemistry A 116(12):3124-3136.  doi:10.1021/jp2115753
  • Yoo S, and SS Xantheas. 2012. "Enhancement of Hydrogen Storage Capacity in Hydrate Lattices." Chemical Physics Letters 525-526:13-18.  doi:10.1016/j.cplett.2011.12.036
  • Yoo S, and SS Xantheas. 2012. "Structures, Energetics and Spectroscopic Fingerprints of Water Clusters n = 2-24." Chapter 21 in Handbook of Computational Chemistry, vol. 2, ed. J. Leszczynski, pp. 761-792.  Springer, New York, NY. 


  • Kaneko S, Y Inokuchi, T Ebata, E Apra, and SS Xantheas. 2011. "Laser Spectroscopic and Theoretical Studies of Encapsulation Complexes of Calix[4]arene." Journal of Physical Chemistry A 115(40):10846-10853.  doi:10.1021/jp204577j
  • Liu J, WH Miller, GS Fanourgakis, SS Xantheas, S Imoto, and S Saito. 2011. "Insights in Quantum Dynamical Effects in the Infrared Spectroscopy of Liquid Water from a Semiclassical Study with an ab Initio-Based Flexible and Polarizable Force Field." Journal of Chemical Physics 135(24):244503.  doi:10.1063/1.3670960
  • Wang XB, and SS Xantheas. 2011. "Photodetachment of Isolated Bicarbonate Anion: Electron Binding Energy of HCO3-." The Journal of Physical Chemistry Letters 2(10):1204-1210.  doi:10.1021/jz200327f
  • Werhahn JC, S Pandelov, S Yoo, SS Xantheas, and H Iglev. 2011. "Dynamics of Confined Water Molecules in Aqueous Salt Hydrates." In Ultrafast Phenomena XVII: Proceedings of the 17th International Conference, July 18-23, 2010, Snowmass, CO, ed. M Chergui, D Jonas, E Riedle, RW Schoenlein and AJ Taylor, pp. 463-465.  Oxford University Press, Oxford, United Kingdom. 
  • Werhahn JC, S Pandelov, SS Xantheas, and H Iglev. 2011. "Dynamics of Weak, Bifurcated and Strong Hydrogen Bonds in Lithium Nitrate Trihydrate." The Journal of Physical Chemistry Letters 2(13):1633-1638.  doi:10.1021/jz200591v
  • Whiteside A, SS Xantheas, and MS Gutowski. 2011. "Is Electronegativity a Useful Descriptor for the "Pseudo-Alkali-Metal" NH4?" Chemistry - A European Journal 17(47):13105.  doi:10.1002/chem.201190241
  • Yoo S, and SS Xantheas. 2011. "Communication: The Effect of Dispersion Corrections on the Melting Temperature of Liquid Water." Journal of Chemical Physics 134(12):Article No. 121105.  doi:10.1063/1.3573375
  • Yoo S, and SS Xantheas. 2011. "The role of hydrophobic surfaces in altering water mediated peptide-petide interactions in an aqueous environment." Journal of Physical Chemistry A 115(23):6088-6092.  doi:10.1021/jp1107137


  • Bakalbassis EG, E Malamidou-Xenikaki, S Spyroudis, and SS Xantheas. 2010. "Dimerization of Indanedioneketene to Spiro-oextanone: A Theoretical Study." Journal of Organic Chemistry 75(16):5499-5504.  doi:10.1021/jo100500u
  • Ebata T, N Hontama, Y Inokuchi, T Haino, E Apra, and SS Xantheas. 2010. "Encapsulation of Arn complexes by Calix[4]arene: Endo- vs. exo-complexes." Physical Chemistry Chemical Physics. PCCP 12(18):4569-4579.  doi:10.1039/b927441c
  • Glezakou VA, ST Elbert, SS Xantheas, and K Ruedenberg. 2010. "Analysis of Bonding Patterns in the Valence Isoelectronic series O-3, S-3, SO2 and OS2 in Terms of Oriented Quasi-Atomic Molecular Orbitals ." Journal of Physical Chemistry A 114(33):8923-8931. 
  • Hontama N, Y Inokuchi, T Ebata, C Dedonder-Lardeau, C Jouvet, and SS Xantheas. 2010. "The structure of the Calix[4]arene-(H2O) Cluster: The World's Smallest Cup of Water." Journal of Physical Chemistry A 114(9):2967-2972. 
  • Kusaka R, Y Inokuchi, SS Xantheas, and T Ebata. 2010. "Structures and Encapsulation Motifs of Functional Molecules probed by Laser Spectroscopic and Theoretical methods." Sensors 10(4):3519-3548.  doi:10.3390/s100403519
  • Paesani F, S Yoo, HJ Bakker, and SS Xantheas. 2010. "Nuclear Quantum Effects in the Reorientation of Water." The Journal of Physical Chemistry Letters 1(15):2316-2321.  doi:10.1021/jz100734w
  • Pandelov S, JC Werhahn, BM Pilles, SS Xantheas, and H Iglev. 2010. "An empirical correlation between the enthalpy of solution of aqueous salts and their ability to form hydrates." Journal of Physical Chemistry A 114(38):10454-10457.  doi:10.1021/jp106050r
  • Wang XB, K Kowalski, LS Wang, and SS Xantheas. 2010. "Stepwise hydration of the cyanide anion: A temperature-controlled photoelectron spectroscopy and ab initio computational study of CN-(H2O)n(n=2-5)." Journal of Chemical Physics 132(12):124306/1-10.  doi:10.1063/1.3360306
  • Xantheas SS, and MS Gordon. 2010. "A Tribute to Klaus Ruedenberg." Journal of Physical Chemistry 114(33):8489. 
  • Yoo S, E Apra, XC Zeng, and SS Xantheas. 2010. "High-Level ab initio electronic structure calculations of Water Clusters (H2O)16 and (H2O)17: a new global minimum for (H2O)16." The Journal of Physical Chemistry Letters 1(20):3122-3127.  doi:10.1021/jz101245s


  • Apra E, AP Rendell, RJ Harrison, V Tipparaju, WA De Jong, and SS Xantheas. 2009. "Liquid Water: Obtaining the right answer for the right reasons." In Proceedings of the Conference on High Performance Computing Networking, Storage and Analysis (SC '09), November 14-20, 2009, Portland, Oregon.  Association for Computing Machinery, New York, NY.  doi:10.1145/1654059.1654127
  • Hammond JR, N Govind, K Kowalski, J Autschbach, and SS Xantheas. 2009. "Accurate dipole polarizabilities for water clusters n=2-12 at the coupled-cluster level of theory and benchmarking of various density functionals." Journal of Chemical Physics 131(21):Article Number:214103. 
  • Paesani F, SS Xantheas, and GA Voth. 2009. "Infrared Spectroscopy and Hydrogen-Bond Dynamics of Liquid Water from Centroid Molecular Dynamics with an Ab Initio-Based Force Field." Journal of Physical Chemistry B 113(39):13118-13130. 
  • Sun X, S Yoo, SS Xantheas, and LX Dang. 2009. "The Reorientation Mechanism of Hydroxide Ions in Water: A Molecular Dynamics Study." Chemical Physics Letters 481(1-3):9-16. 
  • Wang XB, JC Werhahn, LS Wang, K Kowalski, A Laubereau, and SS Xantheas. 2009. "Observation of a remarkable temperature effect in the hydrogen bonding structure and dynamics of the CN-(H2O) cluster." Journal of Physical Chemistry A 113(35):9579-9584. 
  • Xantheas SS, and GA Voth. 2009. "Aqueous Solutions and their Interfaces." Journal of Physical Chemistry B 113(13):3997-3999. 
  • Xantheas SS. 2009. "COMPUTATIONAL CHEMISTRY Dances with hydrogen cations." Nature 457(7230):673-674. 
  • Yoo S, MV Kirov, and SS Xantheas. 2009. "Low-energy networks of the T-cage (H2O)(24) cluster and their use in constructing periodic unit cells of the structure I (sl) hydrate lattice." Journal of the American Chemical Society 131(22):7564-7566. 
  • Yoo S, SS Xantheas, and XC Zeng. 2009. "The Melting Temperature of Bulk Silicon from ab initio Molecular Dynamics Simulations." Chemical Physics Letters 481(1-3):88-90. 
  • Yoo S, XC Zeng, and SS Xantheas. 2009. "On the phase diagram of water with density functional theory potentials: the melting temperature of Ice I-h with the Perdew-Burke-Ernzerhof and Becke-Lee-Yang-Parr functionals." Journal of Chemical Physics 130(22):Art. No. 211102. 



  • Blake TA, ED Glendening, RL Sams, SW Sharpe, and SS Xantheas. 2007. "High Resolution Infrared Spectroscopy in the 1200--1300 cm-1 Region and Accurate Theoretical Estimates for the Structure and Ring-Puckering Barrier of Perfluorocyclobutane." Journal of Physical Chemistry A 111(44):11328-11341.  doi:10.1021/jp072521f



  • Garrett BC, DA Dixon, DM Camaioni, DM Chipman, MA Johnson, CD Jonah, GA Kimmel, JH Miller, T Rescigno, PJ Rossky, SS Xantheas, SD Colson, AH Laufer, D Ray, PF Barbara, DM Bartels, KH Bowen, KH Becker, SE Bradforth, I Carmichael, JV Coe, LR Corrales, JP Cowin, M Dupuis, KB Eisenthal, JA Franz, MS Gutowski, KD Jordon, BD Kay, JA La Verne, SV Lymar, TE Madey, CW Mccurdy, D Meisel, S Mukamel, AR Nilsson, TM Orlando, NG Petrik, SM Pimblott, JR Rustad, GK Schenter, SJ Singer, A Tokmakoff, LS Wang, C Wittig, and TS Zwier. 2005. "Role of Water in Electron-Initiated Processes and Radical Chemistry: Issues and Scientific Advances." Chemical Reviews 105(1):355-389.  doi:10.1021/cr030453x








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