Himadri Pathak
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View article: The First Selected Configuration Interaction Implementation with Distributed Storage of the Configuration Interaction Vector
The First Selected Configuration Interaction Implementation with Distributed Storage of the Configuration Interaction Vector Open
In recent years, the hybrid "QC+HPC" strategy -- where quantum computers screen important determinants, followed by exact diagonalization on classical computer -- has shown great potential in the study of strongly correlated systems in qua…
View article: Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green’s functions
Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green’s functions Open
In this paper, we analyze the properties of the recently proposed real-time equation-of-motion coupled-cluster (RT-EOM-CC) cumulant Green’s function approach [Rehr et al., J. Chem. Phys. 152, 174113 (2020)]. We specifically focus on identi…
View article: Electronic structure simulations in the cloud computing environment
Electronic structure simulations in the cloud computing environment Open
The transformative impact of modern computational paradigms and technologies, such as high-performance computing (HPC), quantum computing, and cloud computing, has opened up profound new opportunities for scientific simulations. Scalable c…
View article: Quantum Electrodynamics Coupled-Cluster Theory: Exploring Photon-Induced Electron Correlations
Quantum Electrodynamics Coupled-Cluster Theory: Exploring Photon-Induced Electron Correlations Open
We present our successful implementation of the quantum electrodynamics coupled-cluster method with single and double excitations (QED-CCSD) for electronic and bosonic amplitudes, covering both individual and mixed excitation processes wit…
View article: Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green's functions
Exploring the exact limits of the real-time equation-of-motion coupled cluster cumulant Green's functions Open
In this paper, we analyze the properties of the recently proposed real-time equation-of-motion coupled-cluster (RT-EOM-CC) cumulant Green's function approach [J. Chem. Phys. 2020, 152, 174113]. We specifically focus on identifying the limi…
View article: TAMM: Tensor algebra for many-body methods
TAMM: Tensor algebra for many-body methods Open
Tensor algebra operations such as contractions in computational chemistry consume a significant fraction of the computing time on large-scale computing platforms. The widespread use of tensor contractions between large multi-dimensional te…
View article: Time-dependent multiconfiguration self-consistent-field and time-dependent optimized coupled-cluster methods for intense laser-driven multielectron dynamics
Time-dependent multiconfiguration self-consistent-field and time-dependent optimized coupled-cluster methods for intense laser-driven multielectron dynamics Open
We reviewed the time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method and the time-dependent optimized coupled-cluster (TD-OCC) method for first-principles simulations of high-field phenomena such as tunneling ionizatio…
View article: Real-time Equation-of-Motion Coupled-Cluster Cumulant Green's Function Method: Heterogeneous Parallel Implementation Based on the Tensor Algebra for Many-body Methods Infrastructure
Real-time Equation-of-Motion Coupled-Cluster Cumulant Green's Function Method: Heterogeneous Parallel Implementation Based on the Tensor Algebra for Many-body Methods Infrastructure Open
We report the implementation of the real-time equation-of-motion coupled-cluster (RT-EOM-CC) cumulant Green's function method [J. Chem. Phys. 152, 174113 (2020)] within the Tensor Algebra for Many-body Methods (TAMM) infrastructure. TAMM i…
View article: ExaChem/exachem
ExaChem/exachem Open
Open Source Exascale Computational Chemistry Software
View article: Time-dependent multiconfiguration self-consistent-field and time-dependent optimized coupled-cluster methods for intense laser-driven multielectron dynamics
Time-dependent multiconfiguration self-consistent-field and time-dependent optimized coupled-cluster methods for intense laser-driven multielectron dynamics Open
We review time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method and time-dependent optimized coupled-cluster (TD-OCC) method for first-principles simulations of high-field phenomena such as tunneling ionization and high…
View article: Time-dependent optimized coupled-cluster method with doubles and perturbative triples for first principles simulation of multielectron dynamics
Time-dependent optimized coupled-cluster method with doubles and perturbative triples for first principles simulation of multielectron dynamics Open
We report the formulation of a new, cost-effective approximation method in the time-dependent optimized coupled-cluster (TD-OCC) framework [T. Sato et al. , J. Chem. Phys. 148, 051101 (2018)] for first-principles simulations of multielectr…
View article: Time-dependent optimized coupled-cluster method with doubles and perturbative triples [TD-OCCD(T)] for first principles simulation of multielectron dynamics
Time-dependent optimized coupled-cluster method with doubles and perturbative triples [TD-OCCD(T)] for first principles simulation of multielectron dynamics Open
We report the formulation of a new, cost-effective approximation method in the time-dependent optimized coupled-cluster (TD-OCC) framework [T. Sato et al., J. Chem. Phys. 148, 051101 (2018)] for first-principles simulations of multielectro…
View article: Real-time equation-of-motion CC cumulant and CC Green’s function simulations of photoemission spectra of water and water dimer
Real-time equation-of-motion CC cumulant and CC Green’s function simulations of photoemission spectra of water and water dimer Open
Newly developed coupled-cluster (CC) methods enable simulations of ionization potentials and spectral functions of molecular systems in a wide range of energy scales ranging from core-binding to valence. This paper discusses the results ob…
View article: Real-time equation-of-motion CC cumulant and CC Green's function simulations of photoemission spectra of water and water dimer
Real-time equation-of-motion CC cumulant and CC Green's function simulations of photoemission spectra of water and water dimer Open
Newly developed coupled-cluster (CC) methods enable simulations of ionization potentials and spectral functions of molecular systems in a wide range of energy scales ranging from core-binding to valence. This paper discusses results obtain…
View article: Time-dependent optimized coupled-cluster method for multielectron dynamics. IV. Approximate consideration of the triple excitation amplitudes
Time-dependent optimized coupled-cluster method for multielectron dynamics. IV. Approximate consideration of the triple excitation amplitudes Open
We present a cost-effective treatment of the triple excitation amplitudes in the time-dependent optimized coupled-cluster (TD-OCC) framework called TD-OCCDT(4) for studying intense laser-driven multielectron dynamics. It considers triple e…
View article: Study of laser-driven multielectron dynamics of Ne atom using time-dependent optimised second-order many-body perturbation theory
Study of laser-driven multielectron dynamics of Ne atom using time-dependent optimised second-order many-body perturbation theory Open
We calculate the high-harmonic generation (HHG) spectra, strong-field ionisation, and time-dependent dipole-moment of Ne using explicitly time-dependent optimised second-order many-body perturbation method (TD-OMP2) where both orbitals and…
View article: Study of laser-driven multielectron dynamics of Ne atom using time-dependent optimized second-order many-body perturbation theory
Study of laser-driven multielectron dynamics of Ne atom using time-dependent optimized second-order many-body perturbation theory Open
We calculate the high-harmonic generation (HHG) spectra, strong-field ionization, and time-dependent dipole-moment of Ne using explicitly time-dependent optimized second-order many-body perturbation method (TD-OMP2) where both orbitals and…
View article: Time-dependent optimized coupled-cluster method for multielectron dynamics. II. A coupled electron-pair approximation
Time-dependent optimized coupled-cluster method for multielectron dynamics. II. A coupled electron-pair approximation Open
We report the implementation of a cost-effective approximation method within the framework of the time-dependent optimized coupled-cluster (TD-OCC) method [T. Sato et al., J. Chem. Phys. 148, 051101 (2018)] for real-time simulations of int…
View article: Relativistic double-ionization equation-of-motion coupled-cluster method: Application to low-lying doubly ionized states
Relativistic double-ionization equation-of-motion coupled-cluster method: Application to low-lying doubly ionized states Open
This article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac–Coulomb Hamiltonian …
View article: Defending Against Intrusion of Malicious UAVs with Networked UAV Defense Swarms
Defending Against Intrusion of Malicious UAVs with Networked UAV Defense Swarms Open
Nowadays, companies such as Amazon, Alibaba, and even pizza chains are pushing forward to use drones, also called UAVs (Unmanned Aerial Vehicles), for service provision, such as package and food delivery. As governments intend to use these…
View article: Relativistic coupled-cluster study of RaF as a candidate for the parity- and time-reversal-violating interaction
Relativistic coupled-cluster study of RaF as a candidate for the parity- and time-reversal-violating interaction Open
We have employed both the Z-vector method and the expectation-value approach in the relativistic coupled-cluster framework to calculate the scalar-pseudoscalar (S-PS) P, T-odd interaction constant W-s and the effective electric field E-eff…
View article: Search for parity and time reversal violating effects in HgH: Relativistic coupled-cluster study
Search for parity and time reversal violating effects in HgH: Relativistic coupled-cluster study Open
The high effective electric field (Eeff) experienced by the unpaired electron in an atom or a molecule is one of the key ingredients in the success of electron electric dipole moment (eEDM) experiment and its precise calculation requires a…
View article: Implementation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Z</mml:mi></mml:math>-vector method in the relativistic-coupled-cluster framework to calculate first-order energy derivatives: Application to the SrF molecule
Implementation of the-vector method in the relativistic-coupled-cluster framework to calculate first-order energy derivatives: Application to the SrF molecule Open
The molecular dipole moment and magnetic hyperfine structure constant demand\nan accurate wavefunction far from the nucleus and in near nuclear region,\nrespectively. We, therefore, employ the so-called Z-vector method in the domain\nof re…
View article: Relativistic extended-coupled-cluster method for the magnetic hyperfine structure constant
Relativistic extended-coupled-cluster method for the magnetic hyperfine structure constant Open
This article deals with the general implementation of 4-component spinor\nrelativistic extended coupled cluster (ECC) method to calculate first order\nproperty of atoms and molecules in their open-shell ground state configuration.\nThe imp…