5 papers
Occupancy Extrapolation: Reaching Many Excited Electronic States from Ground State Calculations
Yichen Fan, Weitao Yang
The SCF DFT approach defines the system energy as a function of orbital occupancy. Inspired by Landau Fermi liquid theory, we develop an occupancy extrapolation (OE) method tha…
Derivative Discontinuity in Many-Body Perturbation Theory and Chemical Potentials in Random Phase Approximation
Jiachen Li, Weitao Yang
We derive analytical expressions for chemical potentials within the random phase approximation (RPA), equivalently the energy functional evaluated using non interacting Green'…
Velocity Gauge for Oscillator Strength in SCF theory
Yang Shen, Yichen Fan, Weitao Yang
Delta self-consistent-field (SCF) theory is widely used for electronic excitation energy calculations. However, calculating the corresponding oscillator strengths is challengin…
Orbital Energies Are Chemical Potentials in Ground-State Density Functional Theory and Excited-State SCF Theory
Weitao Yang, Yichen Fan
We prove the general chemical potential theorem: the noninteracting one-electron orbital energies in DFT ground states and SCF excited states are corresponding chemical potenti…
Fractional Charges, Linear Conditions and Chemical Potentials for Excited States in Theory
Weitao Yang, Yichen Fan
To describe excited states, the electron density alone being insufficient, we use the noninteracting reference density matrix based on the recently estab…