Department of Physics,National Taiwan University

Professional Experience:
● Professor, Department of Physics, National Taiwan University (2017.8-present)
● Associate Professor, Department of Physics, National Taiwan University (2013.8-2017.7)
● Assistant Professor, Department of Physics, National Taiwan University (2009.8-2013.7)
● Postdoctoral Fellow, University of California, Berkeley and Lawrence Berkeley National Laboratory (2006.1-2009.6)

Software Development:
● Developer, Q-Chem Inc. (2008-present)

Journal Editorial Boards:
● Editorial Board, International Journal of Quantum Chemistry (2018.3-present)
● Editorial Board, London Journals Press (2016.9-present)
● Editorial Board, International Journal of Advanced Research in Physical Science (2016.8-present)
● Editorial Board, The Open Access Journal of Science and Technology (2016.3-present)
● Editorial Board, Mediterranean Journal of Physics (2016.1-present)
● Editorial Board, Journal of Lasers, Optics & Photonics (2015.9-present)
● Editorial Board, Open Journal of Physical Chemistry (2011.3-present)
● Editorial Board, Chinese Journal of Physics (2017.12-2022.4)

Journal Referees:
● Nature Chemistry
● Nature Communications
● Scientific Reports
● Journal of Chemical Physics
● Journal of Chemical Theory and Computation
● Physical Chemistry Chemical Physics
● Journal of Physical Chemistry Letters
● Journal of Physical Chemistry
● Chemical Science
● Nanoscale
● Journal of Materials Chemistry C
● RSC Advances
● The Chemical Record
● Journal of Computational Chemistry
● International Journal of Quantum Chemistry
● Theoretical Chemistry Accounts
● Molecular Physics
● Chemical Physics Letters
● Journal of Applied Physics
● New Journal of Chemistry
● Communications Chemistry
● Chemistry—A European Journal
● Journal of the Taiwan Institute of Chemical Engineers
● Bulletin of the Chemical Society of Japan
● Molecular Simulation
● Molecules
● Synthetic Metals
● Journal of Electronic Materials
● Computational Materials Science
● Chemistry
● Mathematics
● Symmetry
● Entropy
● Chinese Journal of Physics
● Acta Physico-Chimica Sinica
● Journal of Molecular Graphics and Modelling
● Structural Chemistry
● Journal of Theoretical and Computational Chemistry
● Computation

"The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation." P. A. M. Dirac (1929)
 

To meet the challenge, our group has focused on the development of new quantum-mechanical methods (e.g., thermally-assisted-occupation density functional theory) suitable for the study of nanoscale systems (with 100~1,000,000 electrons), and their applications to novel systems at the nanoscale (e.g., Möbius molecules, triangle-shaped graphene nanoflakes, linear and cyclic carbon chains, linear and cyclic boron nanoribbons) and materials for new energy (e.g., solar cells, hydrogen storage materials). Specific research topics are the following.
 

1. Kohn-Sham Density Functional Theory (KS-DFT)
A. Goal:
a. Exchange Energy Density Functional
b. Correlation Energy Density Functional
c. Linear-Scaling Methods
B. Direction:
a. Self-Interaction Error
b. Noncovalent Interaction Error
c. Static Correlation Error
C. Suitable Systems:
Systems with 100~1,000 electrons (the Schrödinger equation and highly accurate ab initio methods are inappropriate due to their expensive computational costs)
 

2. Thermally-Assisted-Occupation Density Functional Theory (TAO-DFT)
A. Density Functional Approximations
B. Fictitious Temperature
C. Fundamental Properties
D. Extensions
E. Ab Initio Molecular Dynamics
F. Strongly Correlated Electron Systems at the Nanoscale
 

3. Orbital-Free Density Functional Theory
A. Goal:
a. Kinetic Energy Density Functional
b. Pseudopotentials
B. Direction:
a. Linear Response Theory
b. KEDFs in Certain Situations
c. Transferable Pseudopotentials
C. Suitable Systems:
Systems with 1,000~1,000,000 electrons (Kohn-Sham density functional theory is inappropriate due to its high computational cost)
 

4. Time-Dependent Density Functional Theory
A. Exchange-Correlation Action Functional
B. Excited States
C. Real-Time Electron Dynamics
D. Quantum Transport
E. Quantum Hydrodynamics
 

5. Materials for New Energy
A. Organic Solar Cells
B. Hydrogen Storage Materials

Web of Science

Google Scholar

[With a Landmark (11,300+ citations) paper. Total Citations: 21,200+]

(1) Vidar Gudmundsson*, Vram Mughnetsyan, Hsi-Sheng Goan, Jeng-Da Chai, Nzar Rauf Abdullah, Chi-Shung Tang, Valeriu Moldoveanu, and Andrei Manolescu, "Spin Configuration of an Array of Quantum Rings Controlled by Cavity Photons", Phys. Rev. B 111, 115304 (2025). [Times Cited: 0]

(2) Yun-Hsi Lin and Jeng-Da Chai*, "Classical Chaos in a Driven One-Dimensional Quartic Anharmonic Oscillator", Computation 12, 246 (2024). [Times Cited: 0]

(3) Vidar Gudmundsson*, Vram Mughnetsyan, Hsi-Sheng Goan, Jeng-Da Chai, Nzar Rauf Abdullah, Chi-Shung Tang, Valeriu Moldoveanu, and Andrei Manolescu, "Tuning of Paramagnetic and Diamagnetic Cavity Photon Excitations in a Square Array of Quantum Dots in a Magnetic Field", Phys. Rev. B 110, 205301 (2024). [Times Cited: 1]

(4) Chi-Yu Chen and Jeng-Da Chai*, "Effect of Oriented External Electric Fields on the Electronic Properties of Linear Acenes: A Thermally Assisted Occupation DFT Study", Molecules 29, 4245 (2024). [Times Cited: 0]

(5) Vidar Gudmundsson*, Vram Mughnetsyan, Hsi-Sheng Goan, Jeng-Da Chai, Nzar Rauf Abdullah, Chi-Shung Tang, Valeriu Moldoveanu, and Andrei Manolescu, "Magneto-Optical Properties of a Quantum Dot Array Interacting with a Far-Infrared Photon Mode of a Cylindrical Cavity", Phys. Rev. B 109, 235306 (2024). [Times Cited: 3]

(6) Yu-Yang Wang and Jeng-Da Chai*, "Spin Symmetry in Thermally-Assisted-Occupation Density-Functional Theory", Phys. Rev. A 109, 062808 (2024). [Times Cited: 1]

(7) Sonai Seenithurai and Jeng-Da Chai*, "Electronic Properties of Graphene Nano-Parallelograms: A Thermally Assisted Occupation DFT Computational Study", Molecules 29, 349 (2024). [Times Cited: 1] 

(8) Hung-Yi Tsai and Jeng-Da Chai*, "Real-Time Extension of TAO-DFT", Molecules 28, 7247 (2023). [Times Cited: 2] 

(9) Sonai Seenithurai and Jeng-Da Chai*, "TAO-DFT with the Polarizable Continuum Model", Nanomaterials 13, 1593 (2023). [Times Cited: 7] 

(10) Chi-Chun Chen and Jeng-Da Chai*, "Electronic Properties of Hexagonal Graphene Quantum Rings from TAO-DFT", Nanomaterials 12, 3943 (2022). [Times Cited: 3] 

(11) Bo-Jyun Chen and Jeng-Da Chai*, "TAO-DFT Fictitious Temperature Made Simple", RSC Adv. 12, 12193 (2022). [Times Cited: 12] 

(12) Sonai Seenithurai and Jeng-Da Chai*, "Electronic Properties of Carbon Nanobelts Predicted by Thermally-Assisted-Occupation DFT", Nanomaterials 11, 2224 (2021). [Times Cited: 13] 

(13) Evgeny Epifanovsky, Andrew T. B. Gilbert, Xintian Feng, ..., Jeng-Da Chai, ..., Martin Head-Gordon*, John M. Herbert*, and Anna I. Krylov* et al., "Software for the Frontiers of Quantum Chemistry: An Overview of Developments in the Q-Chem 5 Package", J. Chem. Phys. 155, 084801 (2021). [Times Cited: 728]

(14) Shakeel Ahmad Khandy and Jeng-Da Chai*, "Origin of Pseudo Gap and Thermoelectric Signatures of Semimetallic Ru2TaGa: Structural Stability from Phonon Dynamics, Mechanical, and Thermodynamic Predictions", J. Phys. Chem. Solids 154, 110098 (2021). [Times Cited: 37] 

(15) Shakeel Ahmad Khandy and Jeng-Da Chai*, "Strain Engineering of Electronic Structure, Phonon, and Thermoelectric Properties of P-Type Half-Heusler Semiconductor", J. Alloys Compd. 850, 156615 (2021). [Times Cited: 67]

(16) Shaozhi Li and Jeng-Da Chai*, "TAO-DFT-Based Ab Initio Molecular Dynamics", Front. Chem. 8, 589432 (2020). [Times Cited: 9]

(17) Robert van Meer*, Oleg Gritsenko, and Jeng-Da Chai*, "Combining Density-Based Dynamical Correlation with a Reduced-Density-Matrix Strong-Correlation Description", Phys. Rev. A 102, 032815 (2020). [Times Cited: 5]

(18) Shu-Hao Yeh, Aaditya Manjanath, Yuan-Chung Cheng, Jeng-Da Chai*, and Chao-Ping Hsu*, "Excitation Energies from Thermally Assisted-Occupation Density Functional Theory: Theory and Computational Implementation", J. Chem. Phys. 153, 084120 (2020). [Times Cited: 8]

(19) Sonai Seenithurai and Jeng-Da Chai*, "TAO-DFT Investigation of Electronic Properties of Linear and Cyclic Carbon Chains", Sci. Rep. 10, 13133 (2020). [Times Cited: 26]

(20) Hong-Jui Huang, Sonai Seenithurai, and Jeng-Da Chai*, "TAO-DFT Study on the Electronic Properties of Diamond-Shaped Graphene Nanoflakes", Nanomaterials 10, 1236 (2020). [Times Cited: 10]

(21) Shakeel Ahmad Khandy and Jeng-Da Chai*, "Thermoelectric Properties, Phonon, and Mechanical Stability of New Half-Metallic Quaternary Heusler Alloys: FeRhCrZ (Z = Si and Ge)", J. Appl. Phys. 127, 165102 (2020). [Times Cited: 121]

(22) Shakeel Ahmad Khandy and Jeng-Da Chai*, "Robust Stability, Half-Metallic Ferrimagnetism and Thermoelectric Properties of New Quaternary Heusler Material: A First Principles Approach", J. Magn. Magn. Mater. 502, 166562 (2020). [Times Cited: 71]

(23) Qing Deng and Jeng-Da Chai*, "Electronic Properties of Triangle-Shaped Graphene Nanoflakes from TAO-DFT", ACS Omega 4, 14202 (2019). [Times Cited: 20]

(24) Sonai Seenithurai and Jeng-Da Chai*, "Electronic Properties of Linear and Cyclic Boron Nanoribbons from Thermally-Assisted-Occupation Density Functional Theory", Sci. Rep. 9, 12139 (2019). [Times Cited: 12]

(25) Fengyuan Xuan, Jeng-Da Chai*, and Haibin Su*, "Local Density Approximation for the Short-Range Exchange Free Energy Functional", ACS Omega 4, 7675 (2019). [Times Cited: 16]

(26) Jui-Hui Chung and Jeng-Da Chai*, "Electronic Properties of Möbius Cyclacenes Studied by Thermally-Assisted-Occupation Density Functional Theory", Sci. Rep. 9, 2907 (2019). [Times Cited: 19]

(27) Chia-Nan Yeh, Can Wu, Haibin Su*, and Jeng-Da Chai*, "Electronic Properties of the Coronene Series from Thermally-Assisted-Occupation Density Functional Theory", RSC Adv. 8, 34350 (2018). [Times Cited: 21]

(28) Sonai Seenithurai and Jeng-Da Chai*, "Electronic and Hydrogen Storage Properties of Li-Terminated Linear Boron Chains Studied by TAO-DFT", Sci. Rep. 8, 13538 (2018). [Times Cited: 32]

(29) Chih-Ying Lin, Kerwin Hui, Jui-Hui Chung, and Jeng-Da Chai*, "Self-Consistent Determination of the Fictitious Temperature in Thermally-Assisted-Occupation Density Functional Theory", RSC Adv. 7, 50496 (2017). [Times Cited: 33]

(30) Sonai Seenithurai and Jeng-Da Chai*, "Effect of Li Termination on the Electronic and Hydrogen Storage Properties of Linear Carbon Chains: A TAO-DFT Study", Sci. Rep. 7, 4966 (2017). [Times Cited: 26]

(31) Jeng-Da Chai*, "Role of Exact Exchange in Thermally-Assisted-Occupation Density Functional Theory: A Proposal of New Hybrid Schemes", J. Chem. Phys. 146, 044102 (2017). [Times Cited: 42]

(32) Chih-Wei Wang, Kerwin Hui, and Jeng-Da Chai*, "Short- and Long-Range Corrected Hybrid Density Functionals with the D3 Dispersion Corrections", J. Chem. Phys. 145, 204101 (2016). [Times Cited: 25]

(33) Chun-Shian Wu, Pei-Yin Lee, and Jeng-Da Chai*, "Electronic Properties of Cyclacenes from TAO-DFT", Sci. Rep. 6, 37249 (2016). [Times Cited: 49]

(34) Sonai Seenithurai and Jeng-Da Chai*, "Effect of Li Adsorption on the Electronic and Hydrogen Storage Properties of Acenes: A Dispersion-Corrected TAO-DFT Study", Sci. Rep. 6, 33081 (2016). [Times Cited: 44]

(35) Chia-Nan Yeh and Jeng-Da Chai*, "Role of Kekulé and Non-Kekulé Structures in the Radical Character of Alternant Polycyclic Aromatic Hydrocarbons: A TAO-DFT Study", Sci. Rep. 6, 30562 (2016). [Times Cited: 71]

(36) Hsiao-Ling Sun, Wei-Tao Peng, and Jeng-Da Chai*, "Assessment of the LFAs-PBE Exchange-Correlation Potential for High-Order Harmonic Generation of Aligned H2+ Molecules", RSC Adv. 6, 33318 (2016). [Times Cited: 4]

(37) Kerwin Hui and Jeng-Da Chai*, "SCAN-Based Hybrid and Double-Hybrid Density Functionals from Models without Fitted Parameters", J. Chem. Phys. 144, 044114 (2016). [Times Cited: 142]

(38) Yu-Ting Chen, Kerwin Hui, and Jeng-Da Chai*, "The van der Waals Interactions in Rare-Gas Dimers: The Role of Interparticle Interactions", Phys. Chem. Chem. Phys. 18, 3011 (2016). [Times Cited: 9]

(39) Chun-Shian Wu and Jeng-Da Chai*, "Electronic Properties of Zigzag Graphene Nanoribbons Studied by TAO-DFT", J. Chem. Theory Comput. 11, 2003 (2015). [Times Cited: 72]

(40) Yihan Shao, Zhengting Gan, Evgeny Epifanovsky, ..., Jeng-Da Chai, ..., Anna I. Krylov, Peter M. W. Gill, and Martin Head-Gordon* et al., "Advances in Molecular Quantum Chemistry Contained in the Q-Chem 4 Program Package", Mol. Phys. 113, 184 (2015). [Times Cited: 2,561]

(41) Wei-Tao Peng and Jeng-Da Chai*, "Assessment of Asymptotically Corrected Model Potentials for Charge-Transfer-Like Excitations in Oligoacenes", Phys. Chem. Chem. Phys. 16, 21564 (2014). [Times Cited: 7]

(42) Jeng-Da Chai*, "Thermally-Assisted-Occupation Density Functional Theory with Generalized-Gradient Approximations", J. Chem. Phys. 140, 18A521 (2014). [Times Cited: 70]

(43) Chi-Ruei Pan, Po-Tung Fang, and Jeng-Da Chai*, "Asymptotic Correction Schemes for Semilocal Exchange-Correlation Functionals", Phys. Rev. A 87, 052510 (2013). [Times Cited: 10]

(44) Chen-Wei Tsai, Yu-Chuan Su, Guan-De Li, and Jeng-Da Chai*, "Assessment of Density Functional Methods with Correct Asymptotic Behavior", Phys. Chem. Chem. Phys. 15, 8352 (2013). [Times Cited: 48]

(45) Jeng-Da Chai* and Po-Ta Chen, "Restoration of the Derivative Discontinuity in Kohn-Sham Density Functional Theory: An Efficient Scheme for Energy Gap Correction", Phys. Rev. Lett. 110, 033002 (2013). [Times Cited: 47]

(46) Kenji Sumida, David Stuck, Lorenzo Mino, Jeng-Da Chai, Eric D. Bloch, Olena Zavorotynska, Leslie J. Murray, Mircea Dinca, Sachin Chavan, Silvia Bordiga*, Martin Head-Gordon*, and Jeffrey R. Long*, "Impact of Metal and Anion Substitutions on the Hydrogen Storage Properties of M-BTT Metal-Organic Frameworks", J. Am. Chem. Soc. 135, 1083 (2013). [Times Cited: 125]

(47) You-Sheng Lin, Guan-De Li, Shan-Ping Mao, and Jeng-Da Chai*, "Long-Range Corrected Hybrid Density Functionals with Improved Dispersion Corrections", J. Chem. Theory Comput. 9, 263 (2013). [Times Cited: 644]

(48) Jeng-Da Chai* and Shan-Ping Mao, "Seeking for Reliable Double-Hybrid Density Functionals without Fitting Parameters: The PBE0-2 Functional", Chem. Phys. Lett. 538, 121 (2012). [Times Cited: 120]

(49) You-Sheng Lin, Chen-Wei Tsai, Guan-De Li, and Jeng-Da Chai*, "Long-Range Corrected Hybrid Meta-Generalized-Gradient Approximations with Dispersion Corrections", J. Chem. Phys. 136, 154109 (2012). [Times Cited: 99]

(50) Jeng-Da Chai*, "Density Functional Theory with Fractional Orbital Occupations", J. Chem. Phys. 136, 154104 (2012). [Times Cited: 142]

(51) Jeng-Da Chai and Martin Head-Gordon, "Long-Range Corrected Double-Hybrid Density Functionals", J. Chem. Phys. 131, 174105 (2009). [Times Cited: 340]

(52) Jeng-Da Chai and Martin Head-Gordon, "Optimal Operators for Hartree-Fock Exchange from Long-Range Corrected Hybrid Density Functionals", Chem. Phys. Lett. 467, 176 (2008). [Times Cited: 65]

(53) Jeng-Da Chai and Martin Head-Gordon, "Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections", Phys. Chem. Chem. Phys. 10, 6615 (2008). [Times Cited: 11,363]

(54) Jeng-Da Chai and Martin Head-Gordon, "Systematic Optimization of Long-Range Corrected Hybrid Density Functionals", J. Chem. Phys. 128, 084106 (2008). [Times Cited: 3,289]

(55) Jeng-Da Chai and John D. Weeks, "Orbital-Free Density Functional Theory: Kinetic Potentials and Ab Initio Local Pseudopotentials", Phys. Rev. B 75, 205122 (2007). [Times Cited: 40]

(56) Jeng-Da Chai, D. Stroud, J. Hafner, and G. Kresse, "Dynamic Structure Factor of Liquid and Amorphous Ge From Ab Initio Simulations", Phys. Rev. B 67, 104205 (2003). [Times Cited: 39]