Skip to Main Content U.S. Department of Energy
Fundamental and Computational Sciences Directorate

Staff information


Edoardo Apra

Interfacial Sciences & Simulation
Computational Scientist
Pacific Northwest National Laboratory
PO Box 999
MSIN: K8-91
Richland, WA 99352

Research Interests

  • Development of methods and algorithms in electronic structure theory (DFT).
  • Applications of electronic structure methods to problems in catalysis, interfacial science, structural properties of molecules and materials.
  • Implementation of high performance computational algorithms as part of the software development of computational chemistry packages.

Education and Credentials

  • 1993 Ph.D., Physical Chemistry, University of Turin, Turin, Italy
  • 1989 M.S., Chemistry, University of Turin, Turin, Italy

Awards and Recognitions

  • 1999: R&D 100 Award in the Software category for the development of The Molecular Science Software Suite.

PNNL Publications


  • Apra E., J. Warneke, S.S. Xantheas, and X. Wang. 2019. "A benchmark photoelectron spectroscopic and theoretical study of the electronic stability of [B12H12]2-." Journal of Chemical Physics 105, no. 16:164306. PNNL-SA-140650. doi:10.1063/1.5089510
  • Mayer M., V. Van Lessen, M. Rohdenburg, G. Hou, Z. Yang, R.M. Exner, and E. Apra, et al. 2019. "Rational design of an argon-binding superelectrophilic anion." Proceedings of the National Academy of Sciences of the United States of America 116, no. 17:8167-8172. PNNL-SA-140803. doi:10.1073/pnas.1820812116
  • Warneke J., M. Rohdenburg, J.K. Liu, E. Johnson, X. Ma, R. Kumar, and P. Su, et al. 2019. "Gas Phase Fragmentation of Adducts Between Dioxygen and closo-Borate Radical Anions." International Journal of Mass Spectrometry 436. PNNL-SA-136763. doi:10.1016/j.ijms.2018.11.005
  • Warneke J., S.Z. Konieczka, G. Hou, E. Apra, C. Kerpen, F. Keppner, and T.C. Schaefer, et al. 2019. "Properties of perhalogenated {closo-B10} and {closo-B11} multiply charged anions and a critical comparison with {closo-B12} in the gas and the condensed phase." Physical Chemistry Chemical Physics 21, no. 11:5903-5915. PNNL-SA-135487. doi:10.1039/C8CP05313H


  • Chang L., O. Baseggio, L. Sementa, D. Cheng, G. Fronzoni, D. Toffoli, and E. Apra, et al. 2018. "Individual Component Map of Rotatory Strength and Rotatory Strength Density Plots As Analysis Tools of Circular Dichroism Spectra of Complex Systems." Journal of Chemical Theory and Computation 14, no. 7:3703-3714. PNNL-SA-132925. doi:10.1021/acs.jctc.8b00250


  • Agrachev M., S. Antonello, T. Dainese, M. Ruzzi, A. Zoleo, E. Apra, and N. Govind, et al. 2017. "Magnetic Ordering in Gold Nanoclusters." ACS Omega 2, no. 6:2607-2617. PNNL-SA-125554. doi:10.1021/acsomega.7b00472
  • Bylaska E.J., E. Apra, K. Kowalski, M. Jacquelin, W.A. De Jong, A. Vishnu, and B.J. Palmer, et al. 2017. "Transitioning NWChem to the Next Generation of Manycore Machines." In Exascale Scientific Applications: Scalability and Performance Portability, edited by TP Straatsma, KB Antypas and TJ Williams. 165-186. New York, New York:Chapman and Hall/CRC. PNNL-SA-130902.
  • Fischer S.A., E. Apra, N. Govind, W.P. Hess, and P.Z. El-Khoury. 2017. "Non-Equilibrium Chemical Effects in Single Molecule SERS Revealed by ab initio Molecular Dynamics Simulations." Journal of Physical Chemistry A 121, no. 6:1344-1350. PNNL-SA-122695. doi:10.1021/acs.jpca.6b12156
  • Peng B., N. Govind, E. Apra, M. Klemm, J.R. Hammond, and K. Kowalski. 2017. "Coupled Cluster Studies of Ionization Potentials and Electron Affinities of Single-Walled Carbon Nanotubes." Journal of Physical Chemistry A 121, no. 6:1328-1335. PNNL-SA-122228. doi:10.1021/acs.jpca.6b10874
  • Rambukwella M., S. Burrage, M. Neubrander, O. Baseggio, E. Apra, M. Stener, and A. Fortunelli, et al. 2017. "Au38(SPh)24: Au38 Protected with Aromatic Thiolate Ligands." The Journal of Physical Chemistry Letters 8, no. 7:1530-1537. PNNL-SA-122665. doi:10.1021/acs.jpclett.7b00193
  • Sementa L., G. Barcaro, O. Baseggio, M. De Vetta, A. Dass, E. Apra, and M. Stener, et al. 2017. "Ligand-Enhanced Optical Response of Gold Nanomolecules and Its Fragment Projection Analysis: The Case of Au30(SR)18." Journal of Physical Chemistry C 121, no. 20:10832-10842. PNNL-SA-123164. doi:10.1021/acs.jpcc.6b12029
  • Yu C., W. Harbich, L. Sementa, L. Ghiringhelli, E. Apra, M. Stener, and A. Fortunelli, et al. 2017. "Intense Fluorescence of Au20." Journal of Chemical Physics 147, no. 7:074301. PNNL-SA-121242. doi:10.1063/1.4996687


  • Dass A., T.C. Jones, M. Rambukwella, D. Crasto, K.J. Gagnon, L. Sementa, and M. De Vetta, et al. 2016. "Crystal Structure and Theoretical Analysis of Green Gold Au30(S-tBu)18 Nanomolecules and its Relation to Au30S(S-tBu)18." Journal of Physical Chemistry C 120, no. 11:6256-6261. PNNL-SA-116252. doi:10.1021/acs.jpcc.6b00062
  • El-Khoury P.Z., P. Abellan, R.L. Chantry, Y. Gong, A.G. Joly, I.V. Novikova, and J.E. Evans, et al. 2016. "The information content in single-molecule Raman nanoscopy." Advances in Physics: X 1, no. 1:35-54. PNNL-SA-114470. doi:10.1080/23746149.2016.1140010
  • Fang Z., J.H. Both, S. Li, S. Yue, E. Apra, M. Keceli, and A.F. Wagner, et al. 2016. "Benchmark Calculations of Energetic Properties of Groups 4 and 6 Transition Metal Oxide Nanoclusters Including Comparison to Density Functional Theory." Journal of Chemical Theory and Computation 12, no. 8:3689-3710. PNNL-SA-118060. doi:10.1021/acs.jctc.6b00464
  • Hu H., Y. Zhao, J.R. Hammond, E.J. Bylaska, E. Apra, H.J. van Dam, and J. Li, et al. 2016. "Theoretical studies of the global minima and polarizabilities of small lithium clusters." Chemical Physics Letters 644. PNNL-SA-107717. doi:10.1016/j.cplett.2015.11.049
  • Miliordos E., E. Apra, and S.S. Xantheas. 2016. "A New, Dispersion - Driven Intermolecular Arrangement for the Benzene -Water Octamer Complex: Isomers and Analysis of their Vibrational Spectra." Journal of Chemical Theory and Computation 12, no. 8:4004-4014. PNNL-SA-114248. doi:10.1021/acs.jctc.6b00668
  • Ueltschi T.W., S.A. Fischer, E. Apra, A.N. Tarnovsky, N. Govind, P.Z. El-Khoury, and W.P. Hess. 2016. "Time-Domain Simulations of Transient Species in Experimentally Relevant Environments." Journal of Physical Chemistry A 120, no. 4:556-561. PNNL-SA-114738. doi:10.1021/acs.jpca.5b11710


  • Apra E., K. Kowalski, J.R. Hammond, and M. Klemm. 2015. "NWChem: Quantum Chemistry Simulations at Scale." In High Performance Parallelism Pearls - Multicore and Many-core Programming Approaches. 287-306. Waltham, Massachusetts:Morgan Kaufmann. PNNL-SA-104436.
  • Nimmala P., S. Theivendran, G. Barcaro, L. Sementa, C. Kumara, V. Jupally, and E. Apra, et al. 2015. "Transformation of Au-144(SCH2CH2Ph)60 to Au133(SPh-tBu)52)Nanomolecules: Theoretical and Experimental Study." The Journal of Physical Chemistry Letters 6, no. 11:2134-2139. PNNL-SA-109602. doi:10.1021/acs.jpclett.5b00780


  • Anisimov V., G.H. Bauer, K. Chadalavada, R.M. Olson, J.W. Glenski, W.T. Kramer, and E. Apra, et al. 2014. "Optimization of the Coupled Cluster Implementation in NWChem on Petascale Parallel Architectures." Journal of Chemical Theory and Computation 10, no. 10:4307-4316. PNNL-SA-99193. doi:10.1021/ct500404c
  • Apra E., M. Klemm, and K. Kowalski. 2014. "Efficient Implementation of Many-body Quantum Chemical Methods on the Intel Xeon Phi Coprocessor." In International Conference for High Performance Computing, Networking, Storage and Analysis (SC14), November 16-21, 2014, New Orleans, Louisiana, 674-684. Piscataway, New Jersey:IEEE. PNNL-SA-102322. doi:10.1109/SC.2014.60
  • Hu H., K. Bhaskaran-Nair, E. Apra, N. Govind, and K. Kowalski. 2014. "Toward enabling large-scale open-shell equation-of-motion coupled cluster calculations: triplet states of ß-carotene." Journal of Physical Chemistry A 118, no. 39:9087-9093. PNNL-SA-101464. doi:10.1021/jp5021214
  • Miliordos E., E. Apra, and S.S. Xantheas. 2014. "Benchmark Theoretical Study of the p-p Binding Energy in the Benzene Dimer." Journal of Physical Chemistry A 118, no. 35:7568-7578. PNNL-SA-101408. doi:10.1021/jp5024235
  • Shan H., B.M. Austin, W.A. De Jong, L. Oliker, N.J. Wright, and E. Apra. 2014. "Performance Tuning of Fock Matrix and Two-Electron Integral Calculations for NWChem on Leading HPC Platforms." In 4th International Workshop on High Performance Computing Systems. Performance Modeling, Benchmarking and Simulation (PMBS13), November 18, 2013, Denver, Colorado. Lecture Notes in Computer Science, edited by SA Jarvis, SA Wrigth and SD Hammond, 8551, 261-280. New York, New York:Springer. PNNL-SA-99759. doi:10.1007/978-3-319-10214-6_13


  • Bhaskaran-Nair K., W. Ma, S. Krishnamoorthy, O. Villa, H.J. van Dam, E. Apra, and K. Kowalski. 2013. "Noniterative Multireference Coupled Cluster Methods on Heterogeneous CPU-GPU Systems." Journal of Chemical Theory and Computation 9, no. 4:1949-1957. PNNL-SA-92866.
  • Cheng D., F.R. Negreiros, E. Apra, and A. Fortunelli. 2013. "Computational approaches to the chemical conversion of carbon dioxide." ChemSusChem 6, no. 6:944-965. PNNL-SA-94086. doi:10.1002/cssc.201200872
  • Miliordos E., E. Apra, and S.S. 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, no. 11:114302-13. PNNL-SA-97024. doi:10.1063/1.4820448
  • Varga T., T.C. Droubay, M.E. Bowden, R.J. Colby, S. Manandhar, V. Shutthanandan, and D. Hu, et al. 2013. "Coexistence of Weak Ferromagnetism and Polar Lattice Distortion in Epitaxial NiTiO3 thin films of the LiNbO3-Type Structure." Journal of Vacuum Science and Technology B--Microelectronics and Nanometer Structures 31, no. 3:Article No. 030603. PNNL-SA-92833. doi:10.1116/1.4801664


  • Bhaskaran-Nair K., J. Brabec, E. Apra, H.J. van Dam, J. Pittner, and K. Kowalski. 2012. "Implementation of the multireference Brillouin-Wigner and Mukherjee’s coupled cluster methods with non-iterative triple excitations utilizing reference-level parallelism." Journal of Chemical Physics 137, no. 9:094112-1 to 094112-12. PNNL-SA-88195. doi:10.1063/1.4747698
  • Brabec J., J. Pittner, H.J. van Dam, E. Apra, and K. Kowalski. 2012. "Parallel implementation of multireference coupled-cluster theories based on the reference-level parallelism." Journal of Chemical Theory and Computation 8, no. 2:487-497. PNNL-SA-84133.
  • Negreiros F.R., L. Sementa, G. Barcaro, S. Vajda, E. Apra, and A. Fortunelli. 2012. "CO Oxidation by Subnanometer AgxAu3-x Supported Clusters via Density Functional Theory Simulations." ACS Catalysis 2, no. 9:1860-1864. PNNL-SA-90864. doi:10.1021/cs300275v


  • Kaneko S., Y. Inokuchi, T. Ebata, E. Apra, and S.S. Xantheas. 2011. "Laser Spectroscopic and Theoretical Studies of Encapsulation Complexes of Calix[4]arene." Journal of Physical Chemistry A 115, no. 40:10846-10853. PNNL-SA-80093. doi:10.1021/jp204577j
  • Kowalski K., R.M. Olson, S. Krishnamoorthy, V. Tipparaju, and E. Apra. 2011. "Role of Many-Body Effects in Describing Low-Lying Excited States of pi-Conjugated Chromophores: High-Level Equation-of-Motion Coupled-Cluster Studies of Fused Porphyrin Systems." Journal of Chemical Theory and Computation 7, no. 7:2200-2208. PNNL-SA-78691. doi:10.1021/ct200217y
  • Kowalski K., S. Krishnamoorthy, R.M. Olson, V. Tipparaju, and E. Apra. 2011. "Scalable implementations of accurate excited-state coupled cluster theories: application of high-level methods to porphyrin based systems." In Proceedings of International Conference for High Performance Computing, Networking, Storage and Analysis (SC'11), November 12-18, 2011, Seattle, Washington, Article No. 72. New York, New York:Association for Computing Machinery. PNNL-SA-78956. doi:10.1145/2063384.2063481


  • Apra E., R. Ferrando, and A. Fortunelli. 2006. "Density-Functional Global Optimization of Gold Nanoclusters." Physical Review. B, Condensed Matter 73, no. 20:205414 (5 pages). PNNL-SA-48346. doi:10.1103/PhysRevB.73.205414
  • Bulusu S., S. Yoo, E. Apra, S.S. Xantheas, and X. Zeng. 2006. "Lowest-energy structures of water clusters (H2O)(11) and (H2O)(13)." Journal of Physical Chemistry A 110, no. 42:11781-11784. PNNL-SA-50699.
  • Nieplocha J., B.J. Palmer, V. Tipparaju, M. Krishnan, H.E. Trease, and E. Apra. 2006. "Advances, Applications and Performance of the Global Arrays Shared Memory Programming Toolkit." International Journal of High Performance Computing Applications 20, no. 2:203-231. PNNL-SA-45378.
  • Song J., E. Apra, Y. Khait, M.R. Hoffmann, and K. Kowalski. 2006. "High-Level Ab-Initio Calculation on the NiO2 System." Chemical Physics Letters 428, no. 4-6:277-282. PNNL-SA-50204.


  • De Jong W.A., E. Apra, T.L. Windus, J.A. Nichols, R.J. Harrison, K.E. Gutowski, and D.A. Dixon. 2005. "Complexation of the Carbonate, Nitrate, and Acetate Anions with the Uranyl Dication: Density Functional Studies with Relativistic Effective Core Potentials." Journal of Physical Chemistry A 109, no. 50:11568-11577. PNNL-SA-46444. doi:10.1021/jp0541462
  • Fanourgakis G.S., E. Apra, W.A. De Jong, and S.S. Xantheas. 2005. "High-level ab-initio calculations for the four low-lying families of minima of (H2O)20: II. Spectroscopic signatures of the dodecahedron, fused cubes, face-sharing pentagonal prisms, and edge-sharing pentagonal prisms hydrogen bonding networks." Journal of Chemical Physics 122, no. 13:134304. PNNL-SA-43774.
  • Holland D.P., D. Shaw, I. Walker, I.C. McEwen, E. Apra, and M.F. Guest. 2005. "A Study of the Valence Shell Photoelectron and Photoabsorption Spectra of CF3SF5." Journal of Physics. B, Atomic, Molecular and Optical Physics 38, no. 12:2047-2067. PNNL-SA-44623. doi:10.1088/0953-4075/38/12/017
  • Nieplocha J., V. Tipparaju, and E. Apra. 2005. "An Evaluation of Two Implementation Strategies for Optimizing One-Sided Atomic Reduction." In 19th IEEE International Parallel & Distributed Processing Symposium. Los Alamitos, California:IEEE Computer Society. PNNL-SA-43827. doi:10.1109/IPDPS.2005.96


  • Apra E., E.A. Carter, and A. Fortunelli. 2004. "Separability Between Valence and Conduction Bands in Transition Metal Clusters." International Journal of Quantum Chemistry 100, no. 3:277-287. PNNL-SA-37039.
  • Apra E., F. Baletto, R. Ferrando, and A. Fortunelli. 2004. "Amorphization Mechanism of Icosahedral Metal Nanoclusters." Physical Review Letters 93, no. 6. PNNL-SA-41220. doi:10.1103/PhysRevLett.93.065502
  • Bylaska E.J., D.A. Dixon, A.R. Felmy, E. Apra, T.L. Windus, C. Zhan, and P.G. Tratnyek. 2004. "The Energetics of the Hydrogenolysis, Dehydrohalogenation, and Hydrolysis of 4,4'-Dichloro-diphenyl-trichloroethane from Ab Initio Electronic Structure Theory." Journal of Physical Chemistry A 108, no. 27:5883-5893. PNNL-SA-39911.
  • Fanourgakis G.S., E. Apra, and S.S. Xantheas. 2004. "High-level ab initio calculations for the four low-lying families of minima of (H2O)(20): 1. Estimates of MP2/CBS binding energies and comparison with empirical potentials." Journal of Chemical Physics 121, no. 6:2655-2663. PNNL-SA-41351.
  • Xantheas S.S., and E. Apra. 2004. "The Binding Energies of the D2d and S4 Water Octamer Isomers: High-level Electronic Structure and Empirical Potential Results." Journal of Chemical Physics 120, no. 2:823-828. PNNL-SA-39513.


  • Apra E., and A. Fortunelli. 2003. "Density-functional Calculations on Platinum Nanoclusters: Pt-13, Pt-38 and Pt-55." Journal of Physical Chemistry A 107, no. 16:2934-2942. PNNL-SA-36414.
  • Apra E., E.J. Bylaska, D.J. Dean, A. Fortunelli, F. Gao, P. Krstic, and J. Wells, et al. 2003. "NWChem for Materials Science." Computational Materials Science 28, no. 2:209-221. PNNL-SA-38228.
  • Hirata S., C. Zhan, E. Apra, T.L. Windus, and D.A. Dixon. 2003. "A New, Self-Contained Asymptotic Correction Scheme To Exchange-Correlation Potentials For Time-Dependent Density Functional Theory." Journal of Physical Chemistry A 107. PNNL-SA-38880.
  • Nieplocha J., E. Apra, J. Ju, and V. Tipparaju. 2003. "One-sided communication on clusters with Myrinet." Cluster Computing 6, no. 2:115-124. PNNL-SA-37490.
  • Windus T.L., E.J. Bylaska, M. Dupuis, S. Hirata, L.A. Pollack, D.M. Smith, and T. Straatsma, et al. 2003. "NWChem: New Functionality." In 3rd International Conference on Computational Science; Lecture notes in computer science, edited by Sloot, P., 2660, 168-180. Berlin:Springer. PNNL-SA-38145.


  • Nieplocha J., J. Ju, and E. Apra. 2001. "One-Sided Communication on the Myrinet-Based SMP Clusters Using the GM Message-Passing Library." In 15th International Parallel and Distributed Processing Symposium, 30166a. Los Alamitos, California:IEEE Computer Society. PNNL-SA-34075.


  • Kendall R.A., E. Apra, D.E. Bernholdt, E.J. Bylaska, M. Dupuis, G.I. Fann, and R.J. Harrison, et al. 2000. "High Performance Computational Chemistry: An Overview of NWChem a Distributed Parallel Application." Computer Physics Communications 128, no. 1 - 2:260 - 283. PNNL-SA-27337.


  • McCullough E.A., E.A. McCullough, E. Apra, and J.A. Nichols. 1997. "Comparison of the Becke-Lee-Yang-Parr and Becke-Perdew-Wang Exchange-Correlation Functionals for Geometries of Cyclopentadienyl-Transition Metal Complexes." Journal of Physical Chemistry A 101, no. 13:2502-2508. PNNL-SA-28211. doi:10.1021/jp963430d

Science at PNNL

Core Research Areas

User Facilities

Centers & Institutes

Research Highlights

View All Research Highlights & Staff Accomplishments

RSS Feed