Publications (32)
Unconventional phase III of high-pressure solid hydrogen
Sam Azadi, T. D. Kuehne
We reassess the phase diagram of high-pressure solid hydrogen using mean-field and many-body wave function based approaches to determine the nature of phase III of solid hydrogen.…
Nature of the Metallization Transition in Solid Hydrogen
Sam Azadi, N. D. Drummond, W. M. C. Foulkes
We present an accurate study of the static-nucleus electronic energy band gap of solid molecular hydrogen at high pressure. The excitonic and quasiparticle gaps of the , …
Correlation energy of the spin-polarized electron liquid by quantum Monte Carlo
Sam Azadi, N. D. Drummond, Sam. M. Vinko
Variational and diffusion quantum Monte Carlo (VMC and DMC) methods with Slater-Jastrow-backflow trial wave functions are used to study the spin-polarized three-dimensional uniform…
Emergence of Resonating Valence-Bond Correlations in Stretched Graphene
Sam Azadi, A. Principi, T. D. Kühne +1
Electronic correlations in graphene are generally considered weak due to the large bandwidth of its electrons. Here we show that tensile expansion of the honeycomb lattice pro…
High-Pressure Hydrogen Sulfide by Diffusion Quantum Monte Carlo
Sam Azadi, Thomas D. Kühne
We use the diffusion quantum Monte Carlo to revisit the enthalpy-pressure phase diagram of the various products from the different proposed decompositions of HS at pressures ab…
Resonant inelastic x-ray scattering in warm-dense Fe compounds beyond the SASE FEL resolution limit
Alessandro Forte, Thomas Gawne, Karim K. Alaa El-Din +19
Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic technique, providing access to the electronic structure and dynamics of atoms, molecules, and solids. Howe…
Correlation energy of the paramagnetic electron gas at the thermodynamic limit
Sam Azadi, N. D. Drummond, S. M. Vinko
The variational and diffusion quantum Monte Carlo methods are used to calculate the correlation energy of the paramagnetic three-dimensional homogeneous electron gas at intermediat…
The role of van der Waals and exchange interactions in high-pressure solid hydrogen
Sam Azadi, Graeme J. Ackland
We investigate the van der Waals interactions in solid molecular hydrogen structures. We calculate enthalpy and the Gibbs free energy to obtain zero and finite temperature phase di…
A consistent description of the iron dimer spectrum with a correlated single-determinant wave function
Michele Casula, Mariapia Marchi, Sam Azadi +1
We study the iron dimer by using an accurate ansatz for quantum chemical calculations based on a simple variational wave function, defined by a single geminal expanded in molecular…
Accurate Self-Attention Wavefunctions at Large Scale
Filippo Gaggioli, Sam Azadi, Liang Fu
The authors apply self‑attention neural network variational wavefunctions to the two‑dimensional homogeneous electron gas with up to 169 particles, achieving energies lower than st…
Shock-driven amorphization and melt in FeO
Céline Crépisson, Alexis Amouretti, Marion Harmand +28
We present measurements on FeO amorphization and melt under laser-driven shock compression up to 209(10) GPa via time-resolved in situ x-ray diffraction. At 122(3) GPa, a d…
Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo
Sam Azadi, R. E. Cohen
We study the low-pressure (0 to 10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo (QMC) and density functional theory (DFT) methods. We consider the , $P…
Equation of state of atomic solid hydrogen by stochastic many-body wave function methods
Sam Azadi, George H. Booth, Thomas D. Kühne
We report a numerical study of the equation of state of crystalline body-centered-cubic (BCC) hydrogen, tackled with a variety of complementary many-body wave function methods. The…
Nuclear Quantum Effects Induce Metallization of Dense Solid Molecular Hydrogen
Sam Azadi, Ranber Singh, T. D. Kühne
We present an accurate computational study of the electronic structure and lattice dynamics of solid molecular hydrogen at high pressure. The band-gap energies of the , ,…
Low-density Phase Diagram of the Three-Dimensional Electron Gas
Sam Azadi, N. D. Drummond
Variational and diffusion quantum Monte Carlo methods are employed to investigate the zero-temperature phase diagram of the three-dimensional homogeneous electron gas at very low d…
Quasiparticle Effective Mass of the Three-Dimensional Fermi Liquid by Quantum Monte Carlo
Sam Azadi, N. D. Drummond, W. M. C. Foulkes
According to Landau's Fermi liquid theory, the main properties of the quasiparticle excitations of an electron gas are embodied in the effective mass , which determines the en…
Systematic study of finite-size effects in quantum Monte Carlo calculations of real metallic systems
Sam Azadi, Matthew Foulkes
We present a systematic and comprehensive study of finite-size effects in diffusion quantum Monte Carlo calculations of metals. Several previously introduced schemes for correcting…
Resonating Valence Bond Quantum Monte Carlo: Application to the ozone molecule
Sam Azadi, Ranber Singh, Thomas D. Kühne
We study the potential energy surface of the ozone molecule by means of Quantum Monte Carlo simulations based on the resonating valence bond concept. The trial wave function consis…
Modelling of warm dense hydrogen via explicit real time electron dynamics: Dynamic structure factors
Pontus Svensson, Yusuf Aziz, Tobias Dornheim +5
We present two methods for computing the dynamic structure factor for warm dense hydrogen without invoking either the Born-Oppenheimer approximation or the Chihara decomposition, b…
An efficient method for grand-canonical twist averaging in quantum Monte Carlo calculations
Sam Azadi, W. M. C. Foulkes
We introduce a simple but efficient method for grand-canonical twist averaging in quantum Monte Carlo calculations. By evaluating the thermodynamic grand potential instead of the g…
The fate of the resonating valence bond in graphene
Mariapia Marchi, Sam Azadi, Sandro Sorella
We apply a variational wave function capable of describing qualitatively and quantitatively the so called "resonating valence bond" in realistic materials, by improving standard ab…
Anhamonic finite temperature effects on the Raman and Infrared spectra to determine the crystal structure phase III of solid molecular hydrogen
Ranber Singh, Sam Azadi, Thomas D. Kühne
We present theoretical calculations of the Raman and IR spectra, as well as electronic properties at zero and finite temperature to elucidate the crystal structure of phase III of…
Absence of Metallization in Solid Molecular Hydrogen
Sam Azadi, Thomas D. Kühne
Being the simplest element with just one electron and proton the electronic structure of the Hydrogen atom is known exactly. However, this does not hold for the complex interplay b…
Quantum Plasmonic Nanoantennas
Jamie M. Fitzgerald, Sam Azadi, Vincenzo Giannini
We study plasmonic excitations in the limit of few electrons, in one-atom thick sodium chains, and characterize them based on collectivity. We also compare the excitations to class…
Hot Electron-Driven Structural Expansion and Magnetic Collapse in Bilayer FeSe
Sam Azadi, A. Principi, M. S. Bahramy
Quantum phenomena emerging from the interaction of light and matter in low-dimensional systems hold great potential for future quantum technologies. Here, using first-principles ca…
Quantum Monte Carlo study of the phase diagram of the two-dimensional uniform electron liquid
Sam Azadi, N. D. Drummond, S. M. Vinko
We present a study of spin-unpolarized and spin-polarized two-dimensional uniform electron liquids using variational and diffusion quantum Monte Carlo (VMC and DMC) methods with Sl…
Structural evolution of iron oxides melts at Earth's outer-core pressures
Céline Crépisson, Mila Fitzgerald, Domenic Peake +32
Oxygen and other light elements comprise up to 5 wt% of the Earth's outer-core, and may significantly influence its physical properties and the operation of the geodynamo. Here we…
Dissociation of high-pressure solid molecular hydrogen: Quantum Monte Carlo and anharmonic vibrational study
Sam Azadi, Bartomeu Monserrat, W. M. C. Foulkes +1
A theoretical study is reported of the molecular-to-atomic transition in solid hydrogen at high pressure. We use the diffusion quantum Monte Carlo method to calculate the static la…
Electron correlation effects and spin-liquid state in the Herbertsmithite Kagome lattice
Sam Azadi, Kühne
We employ real-space variational quantum Monte Carlo methods with resonating valence bond many-body wave functions to investigate electron correlation effects in the Kagome system…
Chemical accuracy from quantum Monte Carlo for the Benzene Dimer
Sam Azadi, R. E. Cohen
We report an accurate study of interactions between Benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these…
Universal Multifractality at the Topological Anderson Insulator Transition
Ksenija Kovalenka, Ahmad Ranjbar, Sam Azadi +3
Disorder is ubiquitous in quantum materials, and its interplay with topology can generate phases absent in the clean limit. Using the Haldane model as a minimal setting, we show th…
GW space-time method: Energy band-gap of solid hydrogen
Sam Azadi, Arkadiy Davydov, Evgeny Kozik
We implement the GW space-time method at finite temperatures, in which the Green's function G and the screened Coulomb interaction W are represented in the real space on a suitable…