{
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  {
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   "source": [
    "# Calculation of contact angles with cDFT"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "7fcfe24b",
   "metadata": {},
   "outputs": [],
   "source": [
    "import feos\n",
    "import si_units as si\n",
    "import numpy as np\n",
    "\n",
    "# set up fluid model\n",
    "parameters = feos.Parameters.from_json([\"methanol\"], \"../../parameters/pcsaft/esper2023.json\")\n",
    "functional = feos.HelmholtzEnergyFunctional.pcsaft(parameters)\n",
    "\n",
    "# set up surface\n",
    "ext_pot = feos.ExternalPotential.LJ93(sigma_ss=3.0, epsilon_k_ss=120.0, rho_s=0.08)\n",
    "pore = feos.Pore1D(feos.Geometry.Cartesian, 50*si.ANGSTROM, ext_pot)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "70ee72e5",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/latex": [
       "$31.99°$"
      ],
      "text/plain": [
       "31.990466526671963°"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# calculate the density profiles of the vapor and the liquid states\n",
    "vle = feos.PhaseEquilibrium.pure(functional, 350 * si.KELVIN)\n",
    "vapor_profile = pore.initialize(vle.vapor).solve()\n",
    "liquid_profile = pore.initialize(vle.liquid).solve()\n",
    "\n",
    "# calculate the solid/fluid interfacial tensions\n",
    "gamma_sl = liquid_profile.interfacial_tension / si.ANGSTROM**2\n",
    "gamma_sv = vapor_profile.interfacial_tension / si.ANGSTROM**2\n",
    "\n",
    "# calculate the vapor/liquid interfacial tension\n",
    "vle_profile = feos.PlanarInterface.from_pdgt(vle, 2048).solve()\n",
    "gamma_vl = vle_profile.surface_tension\n",
    "\n",
    "# calculate the contact angle from Young's equation\n",
    "np.acos((gamma_sv-gamma_sl)/gamma_vl)*si.RADIANS"
   ]
  }
 ],
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