> dear siesta users > i want to run Ar gas, can i do this by siesta? > if i can, are there any software which i could find coordinate of atoms in > Ar gas? > thanks
Dear roz_gh, you question might have amused some colleagues, including myself, but there is a substance in it. "Yes you can", but you should consider that Siesta manipulates "short-tail" objects; so "most of the time" in a gas there will be no overlap and no interaction between your atoms. But, maybe that's just OK for a gas - the atoms will develop forces only on collisions. Comparing to a planewave method, Siesta might be quite efficient. But how really good? I doubt you'll find software which gives you positions in Ar gas, but a priori, just to start molecular dynamics, you'd need to generate coordinates of atoms in a box of chosen size, taken at a concentration of your choice, using some random numbers generator. (Then you'll run MD for a while anyway, I guess). This might be faster to program yourself than search for a code which does it. However, the real question is, what do you want achieve by "running a gas"? To get its electronic structure and density of states? - Hm. - To check the Mendeleyev-Klapeyron equation? - Good luck. In fact, this may be didactically interesting. (Did anyone did something similar before?) Anyway, I suggest that you have some clear idea of what you want to do before you start calculations. For the future, please: - give a meaningful subject line, to facilitate the search over archives, - sign your messages Best regards Andrei Postnikov
