{
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   "cell_type": "markdown",
   "id": "2f323a90-1e4f-4a27-a495-38dbf8dad3e3",
   "metadata": {},
   "source": [
    "# Surface tension of a pure substance "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "06f40029-24e4-4f91-b502-6b9265818ed8",
   "metadata": {},
   "outputs": [],
   "source": [
    "from feos.si import *\n",
    "from feos.dft import HelmholtzEnergyFunctional, PhaseEquilibrium, PlanarInterface\n",
    "from feos.pcsaft import PcSaftParameters\n",
    "\n",
    "parameters = PcSaftParameters.from_json(\n",
    "    substances=['methanol'], \n",
    "    pure_path='../parameters/pcsaft/gross2002.json'\n",
    ")\n",
    "functional = HelmholtzEnergyFunctional.pcsaft(parameters)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "38b998ad-4fd0-4a1e-8fa3-991a13fc0860",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "||temperature|density|\n",
       "|-|-|-|\n",
       "|phase 1|350.00000 K|62.68366  mol/m³|\n",
       "|phase 2|350.00000 K|23.13883 kmol/m³|\n"
      ],
      "text/plain": [
       "phase 0: T = 350.00000 K, ρ = 62.68366  mol/m³\n",
       "phase 1: T = 350.00000 K, ρ = 23.13883 kmol/m³"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "vle = PhaseEquilibrium.pure(functional, 350 * KELVIN)\n",
    "vle"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "a48aff0e-cdb8-4553-96ff-57328272c184",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/latex": [
       "$20.191\\,\\mathrm{\\frac{mN}{m}}$"
      ],
      "text/plain": [
       "20.1906936921082 mN/m"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "surface_tension_pdgt = (PlanarInterface\n",
    "    .from_pdgt(vle, 1024)\n",
    "    .solve()\n",
    "    .surface_tension)\n",
    "surface_tension_pdgt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "1bb266d3-8dbf-4bbf-833d-42bfee960fe8",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/latex": [
       "$20.191\\,\\mathrm{\\frac{mN}{m}}$"
      ],
      "text/plain": [
       "20.190693551809428 mN/m"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "surface_tension_tanh = (PlanarInterface\n",
    "    .from_tanh(vle, 1024, 100 * ANGSTROM, 500 * KELVIN)\n",
    "    .solve()\n",
    "    .surface_tension\n",
    ")\n",
    "surface_tension_tanh"
   ]
  }
 ],
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