From af1391197c52a59a7fce8382f348d475546923fc Mon Sep 17 00:00:00 2001
From: Nuwan Yapa <yapanuwan@gmail.com>
Date: Tue, 23 Apr 2024 13:40:21 -0400
Subject: [PATCH] 3 boson resonance from ComplexScaling-FV paper

---
 3body_resonance.jl | 52 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 3body_resonance.jl

diff --git a/3body_resonance.jl b/3body_resonance.jl
new file mode 100644
index 0000000..e1d67c5
--- /dev/null
+++ b/3body_resonance.jl
@@ -0,0 +1,52 @@
+using Arpack, SparseArrays
+include("ho_basis.jl")
+include("p_space.jl")
+
+Λ = 0
+m = 1.0
+V_of_r(r) = 2 * exp(-(r-3)^2 / (1.5)^2)
+
+E_max = 24
+μω_global = 0.5 * exp(-2im * pi / 9)
+
+# due to Jacobi coordinates
+μ1ω1 = μω_global * 1/2
+μ2ω2 = μω_global * 2
+μ1 = m * 1/2
+μ2 = m * 2/3
+
+println("No of threads = ", Threads.nthreads())
+
+@time "Basis" begin
+    Es, n1s, l1s, n2s, l2s = get_2p_basis(E_max)
+    l_max = max(maximum(l1s), maximum(l2s))
+    n_max = max(maximum(n1s), maximum(n2s))
+    mask1 = (n2s .== n2s') .&& (l2s .== l2s')
+    mask2 = (n1s .== n1s') .&& (l1s .== l1s')
+end
+
+println("Basis size = ", length(Es))
+
+println("Constructing KE matrices")
+
+@time "T1" T1 = sp_T_matrix(n1s, l1s; mask=mask1, μω_gen=μ1ω1, μ=μ1)
+@time "T2" T2 = sp_T_matrix(n2s, l2s; mask=mask2, μω_gen=μ2ω2, μ=μ2)
+
+println("Constructing PE matrices")
+
+V1_elem(l, n1, n2) = V_numerical(V_of_r, l, n1, n2; μω_gen=μ1ω1)
+V_relative_elem(l, n1, n2) = V_numerical(V_of_r, l, n1, n2; μω_gen=μω_global)
+V1_cache = fill(Complex(NaN), 1+l_max, 1+n_max, 1+n_max)
+V_relative_cache = fill(Complex(NaN), 1+l_max, 1+n_max, 1+n_max)
+
+@time "V1" V1 = sp_V_matrix(V1_elem, n1s, l1s; mask=mask1, dtype=ComplexF64, cache=V1_cache)
+@time "V relative" V_relative = sp_V_matrix(V_relative_elem, n1s, l1s; mask=mask1, dtype=ComplexF64, cache=V_relative_cache) + sp_V_matrix(V_relative_elem, n2s, l2s; mask=mask2, dtype=ComplexF64, cache=V_relative_cache)
+@time "Moshinsky brackets" U = Moshinsky_transform(Es, n1s, l1s, n2s, l2s, Λ)
+@time "V2" V2 =  U' * V_relative * U
+
+println("Calculating spectrum")
+
+@time "H" H = T1 + T2 + V1 + V2
+@time "Eigenvalues" evals, _ = eigs(H, nev=5, ncv=50, which=:LI, maxiter=5000, tol=1e-5, ritzvec=false, check=1)
+
+display(evals)
\ No newline at end of file