We analyze the method for calculation of properties of nonrelativistic quantum systems based on exact diagonalization of space-discretized short-time evolution operators. In this paper we present a detailed analysis of the errors associated with space discretization. Approaches using direct diagonalization of real-space discretized Hamiltonians lead to polynomial errors in discretization spacin...

We present an efficient program for the exact diagonalization solution of pairing Hamiltonian in spherical systems with rotational invariance based on SU(2) quasi-spin algebra. The basis vectors symmetry considered are generated by using iterative algorithm. Then matrix constructed this is diagonalized Lanczos All non-zero elements evaluated “on fly” scattering operator and hash search acting v...

Lattice spin-fermion models are important to study correlated systems where quantum dynamics allows for a separation between slow and fast degrees of freedom. The fast degrees of freedom are treated quantum mechanically while the slow variables, generically referred to as the "spins," are treated classically. At present, exact diagonalization coupled with classical Monte Carlo (ED + MC) is exte...

Full geometry optimizations followed by the vibrational analysis were performed for eight spin configurations of the CaMn4O4X(H2O)3Y (X = O, OH; Y = H2O, OH) cluster in the S1 and S3 states of the oxygen evolution complex (OEC) of photosystem II (PSII). The energy gaps among these configurations obtained by vertical, adiabatic and adiabatic plus zero-point-energy (ZPE) correction procedures hav...

We present a method to determine the model Hamiltonians treat rare-earth multiplets in solids from results of quasiparticle self-consistent \textit{GW} (QSGW) method. apply trivalent Eu compounds EuCl$_3$, EuN, and Eu-doped GaN after examining free ions. solve Hamiltonian by exact diagonalization. Our justify applying Dieke diagram ions solid, while its limitation is clarified. In particular, w...

The finite temperature Lanczos method (FTLM), which is an exact diagonalization intensively used in quantum many-body calculations, formulated the framework of orthogonal polynomials and Gauss quadrature. main idea to reduce static dynamic quantities into weighted summations related one- two-dimensional quadratures. Then lower order quadrature, generated from iteration, can be applied approxima...

We present results from our analysis of the finite-temperature properties of the spin 1/2 J1-J2 Heisenberg model on a square lattice. The analysis is based on the exact diagonalization of small clusters with 16 and 20 sites utilizing the finite-temperature Lanczos method. In particular, we focus on the temperature dependence of the third-order magnetic susceptibility as a method to resolve the ...