Yusuke Nomura's Website
Research Interest
Research Interest
Development of computational methods
Development of computational methods
So far, I have been involved in
- Symmetry adapted Wannier mode in Wannier90 (http://www.wannier.org)
- Constrained density-functional perturbation theory (for deriving electron-phonon coupled Hamiltonian)
- Estimation of interaction parameters tailored for dynamical mean-field solvers
- Implementation of dynamical mean-field solvers (CT-HYB and CT-INT)
- Double-expansion CT-HYB solver to treat retarded exchange interaction (dynamical J)
- Improvement of negative-sign problem in CT-INT by single-particle basis transformation and by efficient treatment of spin-flip and pair-hopping interactions
- Speed up (~ 10 times) of CT-INT solver by the introducing submatrix update
I am now involved in
- Machine-learning solvers to study many-body quantum systems
- RESPACK (https://sites.google.com/view/kazuma7k6r): open-source program for GW, constrained random phase approximation (cRPA), and maximally localized Wannier function
- Implementation of Trilex (independently from the original implementation of Ayral and Parcollet) and its extension to multi-orbital systems
- Development of efficient solver for electron-boson coupled Hamiltonian
- Efficient calculation of two-particle quantities using the idea of sparse modeling
I am also interested in
- Finite-temperature or time-dependent calculation using variational Monte Carlo technique
Strong correlations, strong electron-phonon coupling, and unconventional superconductivity
Strong correlations, strong electron-phonon coupling, and unconventional superconductivity
I use ab initio techniques to study these systems. So far, I have studied
- Alkali-doped fullerides and aromatic superconductors
- Iron-based superconductors
- Cuprate bulk and interface
- Honeycomb lattice iridate Na2IrO3
- Compressed sulfur hybrids H2S and H3S
- Transition metal oxide SrVO3
- (111) bilayers of LaAuO3 and SrIrO3
- Organic conductor (TMTSF)2PF6
and so on…
In ongoing projects, I am studying
- Cuprates
- Alkali-doped fullerides
- Rare-earth nickelates RNiO3
- Surface adatom systems
- 5d pyrochlore oxide Cd2Os2O7
- Heavy-fermion compound LiV2O4
and so on…
Phonons in strongly-correlated materials
Phonons in strongly-correlated materials
I am interested in how phonons affect electrons and vice versa. For this purpose, I am interested in the development of more efficient/accurate solver for electron-boson coupled Hamiltonians.
Non-equilibrium problems
Non-equilibrium problems
I am especially interested in superconductivity realized in non-equilibrium situation.
Computing Experiences
Computing Experiences
- Band structure calculation (Quantum Espresso, Wien2k, ELK, …)
- Maximally localized Wannier function (Wannier90, Wien2Wannier, RESPACK): I have contributed to the development of version 2.1.0 of Wannier90
- Calculation of response function (e.g. dielectric function) from first principles (RESPACK)
- Phonon calculations using density-functional perturbation theory (Quantum Espresso)
- Ab initio derivation of realistic low-energy Hamiltonian
- One-body part: Maximally localized Wannier function
- Coulomb part: Constrained random phase approximation (cRPA)
- Phonon part: Constrained density-functional perturbation theory (cDFPT)
- Machine learning using Boltzmann machines
- Variational Monte Carlo methods
- Dynamical mean-field theory with continuous-time quantum Monte Carlo method: I have implemented both CT-INT and CT-HYB from scratch
- Extension of DMFT (dynamical interaction, phonon, cellular DMFT, DCA, Trilex, …)
- RPA analysis of superconducting gap equation
- Fortran language, C language, Python (basic)
- Parallel computing (MPI and OpenMP)