arXiv subjects

Petar Sinilkov

Publications and source records attributed to Petar Sinilkov.

3 recordsLinked to original sources

arXiv2026

Low-Temperature Hybrid Monte Carlo for Perylene and Corannulene: Stabilizing Determinant and Force

We demonstrate a real world physics study of the molecules perylene and corannulene at different doping levels, and calculating selected one-, two- (exciton) and three-body (trion) correlators. This has been done by performing Hubbard-model simulations near room temperature. We find, between charge neutral and doubly charged plateaus of perylene, an interaction-induced $ΔQ = 1$ plateau whose width grows with interaction strength and in which the ground state is a spin doublet rather than a singlet. The algorithmic advancement enabling this study simultaneously stabilizes the determinant and force calculations to machine precision at room temperature, while scaling as well as standard determinant Quantum Monte Carlo simulations of these systems. Furthermore, our formalism retains the full time-displaced (2-point) Green's function, allowing us to construct any $n$-body correlator, including those that contain disconnected diagrams.

cond-mat.str-el↗

arXiv2026

Stable Determinant Monte Carlo Simulations at Large Inverse Temperature $β$

At low temperatures $T$ where $1/T=β\gg1$ the naïve implementation of determinant quantum Monte Carlo (DQMC) methods suffers from loss of precision and numerical instabilities when evaluating the fermion determinant. This instability propagates into the calculation of observables that rely on the evaluation of the inverse of the fermion matrix, or the Greens function. For DQMC methods that rely on the Hamiltonian Monte Carlo (HMC) algorithm, an additional complication comes from evaluating the force terms required for integrating Hamilton's equations of motion, since here loss of precision and numerical instabilities are also prevalent. We show how to address all these issues using various choices of matrix decompositions, allowing us to simulate at $β\gtrsim 90$, which corresponds to room temperature for graphene structures. Furthermore, our implementation has numerical costs that scale similarly to the naïve implementation, namely as $\mathcal{O}(N_x^3N_t)$, where $N_x$ ($N_t$) is the number of spatial (temporal) sites.

physics.comp-ph↗

arXiv2025

Search for Stable States in Two-Body Excitations of the Hubbard Model on the Honeycomb Lattice

We present one- and two-body measurements for the Hubbard model on the honeycomb (graphene) lattice from ab-initio quantum monte carlo simulations. Of particular interest is excitons, which are particle/hole excitations in low-dimensional systems. They are analogous to the pion in QCD, but without confinement, the question of whether they are bound and stable is of great interest in the condensed matter arena. By measuring one- and two-body correlators across various spin and isospin channels we can compute two-body energies relative to their thresholds, ultimately allowing us to check for stable states.

cond-mat.str-el↗