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   "source": [
    "# Impurity Solver Tutorial\n",
    "\n",
    "This tutorial goes through using the Hartree-Fock ImpuritySolver for a simple one band case. We start by importing the required modules:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Warning: could not identify MPI environment!\n"
     ]
    },
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Starting serial run at: 2026-06-12 18:12:27.493677\n"
     ]
    }
   ],
   "source": [
    "import numpy as np\n",
    "from triqs.gfs import *\n",
    "from triqs.mesh import MeshImFreq\n",
    "from triqs.operators import *\n",
    "from h5 import HDFArchive\n",
    "from triqs_hartree_fock import ImpuritySolver\n",
    "from triqs.plot.mpl_interface import oplot"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Next we define G0, h_int, and the parameters that we will pass to the solver"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "beta = 40\n",
    "n_iw = 1025\n",
    "\n",
    "iw_mesh = MeshImFreq(beta=beta, statistic='Fermion', n_iw=n_iw)\n",
    "g0 = Gf(mesh=iw_mesh, target_shape=[1,1])\n",
    "g0 << inverse(iOmega_n + 2)\n",
    "G0 = BlockGf(name_list=['up', 'down'], block_list=[g0, g0], make_copies=True)\n",
    "\n",
    "h_int = 3*n('up', 0)*n('down', 0)\n",
    "\n",
    "gf_struct = [('up', 1), ('down', 1)]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now we are ready to initialize the solver:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "S = ImpuritySolver(gf_struct=gf_struct, mesh=iw_mesh)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Next we pass G0 to the solver:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Green Function G composed of 2 blocks: \n",
       " Green's Function G_up with mesh Imaginary frequency mesh with beta = 40, statistics = Fermion, N_iw = 1025, positive_only = false and target_shape (1, 1): \n",
       " \n",
       " Green's Function G_down with mesh Imaginary frequency mesh with beta = 40, statistics = Fermion, N_iw = 1025, positive_only = false and target_shape (1, 1): \n",
       " "
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "S.G0_iw << G0"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Finally, we are ready to call the solve method. By default with_fock is True but can be turned to False to only include Hartree terms."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "╔╦╗╦═╗╦╔═╗ ╔═╗  ┬ ┬┌─┐\n",
      " ║ ╠╦╝║║═╬╗╚═╗  ├─┤├┤\n",
      " ╩ ╩╚═╩╚═╝╚╚═╝  ┴ ┴└\n",
      "TRIQS: Hartree-Fock solver\n",
      "\n",
      "Running Impurity Solver\n",
      "beta = 40.0000\n",
      "h_int =\n",
      "3*c_dag('down',0)*c_dag('up',0)*c('up',0)*c('down',0)\n",
      "HARTREE SOLVER: starting solver in one-shot mode\n",
      "Including Fock terms:\n",
      "True\n",
      "HARTREE SOLVER: Sigma_HF before iterating['up']:\n",
      "[[0.+0.j]]\n",
      "HARTREE SOLVER: Sigma_HF before iterating['down']:\n",
      "[[0.+0.j]]\n",
      "\n",
      "HARTREE SOLVER: fixing dc to 0.0000\n",
      "\n",
      "HARTREE SOLVER: fixing dc to 0.0000\n",
      "HARTREE SOLVER: Sigma_HF['up']:\n",
      "[[3.-0.j]]\n",
      "HARTREE SOLVER: Sigma_HF['down']:\n",
      "[[3.-0.j]]\n",
      "Final G_dens['up']:\n",
      "[[-0.-0.j]]\n",
      "Final G_dens['down']:\n",
      "[[-0.-0.j]]\n"
     ]
    }
   ],
   "source": [
    "S.solve(h_int=h_int, with_fock=True)"
   ]
  }
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