Informal seminar on Chemical Physics: "Classical and quantum simulations in earth, energy and environment systems"
Starts 20 Jun 2011 12:00
Ends 20 Jun 2011 20:00
Central European Time
Leonardo da Vinci Building Luigi Stasi Seminar Room
Strada Costiera, 11
I - 34151 Trieste (Italy)
Recently, we have applied the computational condensed matter physics in liquid-liquid interface, liquid-solid interface and the three phase systems, which we know little in comparison with the bulk condensed matter materials & their surfaces, and are important for earth, energy and environment systems. Of particular, I’ll present three topics, which are relevant to sedimentary Methane Hydrate (MH), CO2 Storage and Sequestration (CCS) and Enhanced Oil Recovery (EOR), respectively.
(1) We have performed molecular dynamics simulations in order to investigate the stability of CH4- and CO2- hydrate. It was found that the cage occupancy of hydrates influences the stability of the hydrates. More importantly, the actual three phase coexistence line of CO2 hydrate may be higher than the value ever measured. Our results show that the “lowered” three phase coexistence line stemmed from the partial occupancy occurred during the lab measurements.
(2) We have investigated the contact angle of CO2/water/silica for two different silica surfaces by using large scale molecular dynamics simulations. It was found that the contact angle increases with pressure for hydrophobic (siloxane) surface while almost constant for the hydrophilic (silanol) surface, which is in excellent agreement with experimental observations. The difference results from the different interactions between the CO2 thin film and silica surfaces.
(3) By using first-principle molecular dynamics, we have studied the interface of new cleaved quartz (0001) surface against liquid water at room temperature. It was found that the quartz surface is not saturated as ideal geminal [Si-(OH)2] surface for all calculations. The rest Si-O* radicals, presumably negatively charged, may help us solve a long-existing mystery in colloid and interface sciences, that the silica surface is negatively charged at PH=7.
In collaboration with Yohei Mikami, Shinya Tsuji, Mia Ledyastuti, Makoto Kunieda and Toshifumi Matsuoka.