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More corrections Holstein compared to PIMC and DMC
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Neutrino155 committed Aug 29, 2023
1 parent 88c09ff commit d1e79c1
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12 changes: 6 additions & 6 deletions src/HolsteinTheory.jl
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Expand Up @@ -34,17 +34,17 @@ end
"""
function holstein_interaction_energy_integrand(τ, v, w, α, ω, β; dims = 3)
coupling = holstein_coupling(1, α, ω; dims = dims)
propagator = polaron_propagator(τ, v, w, ω, β)
phonon_propagator(τ, ω, β) * (coupling * erf* sqrt(propagator * dims)) / sqrt(2π * propagator))^dims
propagator = polaron_propagator(τ, v, w, ω, β) * dims * 2 / ω
phonon_propagator(τ, ω, β) * (coupling * erf* sqrt(propagator / 2)) / sqrt(2π * propagator))^dims
end

"""
Integrand for imaginary time integral for the holstein interaction energy at zero temperature. Here the k-space integral is evaluated analytically.
"""
function holstein_interaction_energy_integrand(τ, v, w, α, ω; dims = 3)
coupling = holstein_coupling(1, α, ω; dims = dims)
propagator = polaron_propagator(τ, v, w, ω)
phonon_propagator(τ, ω) * (coupling * erf* sqrt(propagator * dims / ω)) / sqrt(2π * propagator))^dims
propagator = polaron_propagator(τ, v, w, ω) * 2 * dims / ω
phonon_propagator(τ, ω) * (coupling * erf* sqrt(propagator / 2)) / sqrt(2π * propagator))^dims
end

"""
Expand All @@ -67,8 +67,8 @@ end
Total free energy for the Holstein model. Here the k-space integral is evaluated analytically.
"""
function holstein_energy(v, w, α, ωβ...; dims = 3)
kinetic_energy = -2 * dims - electron_energy(v, w, ωβ...; dims = dims) / dims
potential_energy = -holstein_interaction_energy(v, w, α, ωβ...; dims = dims) / 2.0^dims
kinetic_energy = -2 * dims - electron_energy(v, w, ωβ...; dims = dims)
potential_energy = -holstein_interaction_energy(v, w, α, ωβ...; dims = dims) * dims
return (kinetic_energy + potential_energy), kinetic_energy, potential_energy
end

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6 changes: 3 additions & 3 deletions src/KSpaceTheory.jl
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ end
Electron-phonon coupling matrix for the Holstein model.
"""
function holstein_coupling(k, α, ω; dims = 3)
(2 * dims * α * ω)^(1/dims)
(dims * α * ω)^(1/dims)
end

"""
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"""
function electron_energy(v, w, ω, β; dims = 3)
# dims / β / ω * (log(v / w) - 1 / 2 * log(2π * ω * β) - log(sinh(v * ω * β / 2) / sinh(w * ω * β / 2))) + dims / 4 * (v^2 - w^2) / v * (coth(v * ω * β / 2) - 2 / (v * ω * β)) * ω
(A(v, w, ω, β) + C(v, w, ω, β)) * dims / 3
(A(v, w, ω, β) + C(v, w, ω, β)) / 3
end

"""
Energy associated with the free electron at zero temperature.
"""
function electron_energy(v, w, ω; dims = 3)
-dims * (v - w) / 2 * ω + (dims / (4 * v)) * (v^2 - w^2) * ω
-(v - w) / 2 * ω + (1 / (4 * v)) * (v^2 - w^2) * ω
end

"""
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