Rai Neeraj, Bhatt Divesh, Siepmann J Ilja, Fried Laurence E
Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, USA.
J Chem Phys. 2008 Nov 21;129(19):194510. doi: 10.1063/1.3006054.
The transferable potentials for phase equilibria (TraPPE) force field was extended to nitro and amino substituents for aromatic rings via parametrization to the vapor-liquid coexistence curves of nitrobenzene and aniline, respectively. These groups were then transferred to model 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Without any further parametrization to solid state data, the TraPPE force field is able to predict TATB's unit cell lengths and angles at 295 K with mean unsigned percentage errors of 0.3% and 1.8% and the specific density within 0.5%. These predictions are comparable in accuracy to the GRBF model [Gee et al., J. Chem. Phys. 120, 7059 (2004)] that was parametrized directly to TATB's solid state properties. Both force fields are able to reproduce the pressure dependence of TATB's unit cell volume, but they underestimate its thermal expansion. Due to its energetic nature and unusually large cohesive energy, TATB is not chemically stable at temperature in its liquid range. Gibbs ensemble simulations allow one to determine TATB's vapor-liquid coexistence curve at elevated temperatures and the predicted critical temperature and density for the TraPPE and GRBF model are 937+/-8 and 1034+/-8 K, and 0.52+/-0.02 and 0.50+/-0.02 gcm(3), respectively.
通过分别对硝基苯和苯胺的气液共存曲线进行参数化，将相平衡可转移势（TraPPE）力场扩展到芳香环的硝基和氨基取代基。然后将这些基团转移到1,3,5 - 三氨基 - 2,4,6 - 三硝基苯（TATB）模型中。在没有对固态数据进行任何进一步参数化的情况下，TraPPE力场能够预测295 K时TATB的晶胞长度和角度，平均无符号百分比误差分别为0.3%和1.8%，以及比密度在0.5%以内。这些预测的准确性与直接针对TATB固态性质进行参数化的GRBF模型[Gee等人，《化学物理杂志》120, 7059 (2004)]相当。两个力场都能够重现TATB晶胞体积的压力依赖性，但它们都低估了其热膨胀。由于其能量性质和异常大的内聚能，TATB在其液体范围内的温度下化学不稳定。吉布斯系综模拟允许人们确定TATB在高温下的气液共存曲线，TraPPE和GRBF模型预测的临界温度和密度分别为937±8和1034±8 K，以及0.52±0.02和0.50±0.02 g/cm³。
