Simulation of ionic liquids with Monte Carlo method

2D-model za simulacijo ionskih tekočin z metodo Monte Carlo je bil razvit za preproste in hitre izračune prilagodljivega sistema ionskih tekočin in vode. Delci so predstavljeni kot diskiioni z grobo zrnatim modelom, voda pa z 2D-core-softened modelom. Velikost ionov je poljubna in kationi so lahko sestavljeni tudi iz več diskov v izbrani rigidni obliki, da bolje ponazorijo ionske tekočine. Simulacije so bile izvedene v NpT-ansamblu, da bi preučili termodinamske lastnosti mešanic ionskih tekočin z vodo in strukturne lastnosti sistema. Opazovan je bil vpliv tlaka in temperature na termodinamske lastnosti in strukturo. Raziskovan je bil vpliv velikosti in oblike kationov na sistem. Opisane so osnovne komponente modelavoda, njene značilnosti in pogosti modeli le-te, nato pa še ionske tekočine, njihove lastnosti in tipična sestava. Predstavljene so osnovne interakcije med diski. Matematični model je bil zapisan s programskim jezikom Fortran in simulacija izvedena pod različnimi pogoji. Vzorčeni so bili notranja energija, kvadrat notranje energije in volumen. Rezultati pokažejo, da model opiše pravilne trende za obnašanje notranje energije in gostote v odvisnosti od temperature in tlaka. S parsko porazdelitveno funkcijo lahko opazujemo notranjo ureditev ter vpliv velikosti in oblike ionov na strukture v sistemu. Toplotna kapaciteta nam pokaže ali je sistem v bližini fazne meje. Raziskovane so lastnosti sistema z različnimi razmerji ionov proti vodi in vpliv velikosti in oblike ionov na sistem.2D-model for Monte Carlo simulations was developed with the goal of simple and quick calculations of a customisable system consisting of ionic liquid and water. Particles were simulated as discs, ions with coarse-grained model and water with 2D-core-softened model. Size of ions is customisable and cations can consist of multiple discs in custom rigid shape to better represent ionic liquids. Simulations were run in NpT ensemble to explore thermodynamic properties of systems made of water and ionic liquids and their structural properties. Effects of pressure and temperature on thermodynamic properties and structure of system were observed. Effects of shape and size of cation particles on the system was observed as well. Basic components of the model are describedwater, it’s properties and common models, together with ionic liquids, their properties and typical composition. Interactions between discs are introduced. Mathematical model was written in Fortran programming language and the simulation ran under various conditions. Internal energy, square of internal energy and volume were sampled. Results show that model describes correct trends for internal energy in relation with temperature and pressure. With radial distribution function we can observe internal structures and effects of ion size and shape on it. Heat capacity can show that system is near phase boundary. Properties of systems with varying ratios of ions to water and effect of size and shape of ions on system are researched