Dopieralski Przemyslaw D, Latajka Zdzislaw, Olovsson Ivar
University of Wroclaw, Faculty of Chemistry, 14 Joliot-Curie Str. 50-383 Wroclaw, Poland, and Department of Materials Chemistry, Ångström Laboratory, SE-751 21 Uppsala, Sweden.
J Chem Theory Comput. 2010 May 11;6(5):1455-61. doi: 10.1021/ct100078w.
The crystal structure of maleic acid, the cis conformer of HOOC-CH═CH-COOH has been investigated by Car-Parrinello molecular dynamics (CPMD) and path integral molecular dynamics (PIMD) simulations. The interesting feature of this compound, compared to the trans conformer, fumaric acid, is that both intra- and intermolecular hydrogen bonds are present. CPMD simulations at 100 K indicate that the energy barrier height for proton transfer is too high for thermal jumps over the barrier in both the intra- and intermolecular hydrogen bonds. Dynamics at 295 K reveal that the occupancy ratio of the proton distribution in both the intra- and intermolecular hydrogen bonds is 0.96/0.04. The time lag between the proton transfers in the intra- and intermolecular hydrogen bonds is in the range of 2-9 fs. This is slightly shorter than the time lag obtained previously for fumaric acid, where only intermolecular hydrogen bonds are present. It is also interesting to notice that in most cases the proton transfer process starts in the intramolecular hydrogen bond and subsequently follows in the intermolecular hydrogen bond. Vibrational spectra of the investigated system and its deuterated analogs HOOC-CH═CH-COOD and DOOC-CH═CH-COOD have been calculated and compared with experimental data.
已通过Car-Parrinello分子动力学（CPMD）和路径积分分子动力学（PIMD）模拟研究了马来酸（HOOC-CH═CH-COOH的顺式构象体）的晶体结构。与反式构象体富马酸相比，该化合物的有趣特征在于同时存在分子内和分子间氢键。100 K下的CPMD模拟表明，质子转移的能垒高度过高，以至于在分子内和分子间氢键中都无法通过热跳跃越过该能垒。295 K下的动力学研究表明，分子内和分子间氢键中质子分布的占有率为0.96/0.04。分子内和分子间氢键中质子转移之间的时间间隔在2-9飞秒范围内。这比之前仅存在分子间氢键的富马酸所获得的时间间隔略短。同样有趣的是，在大多数情况下，质子转移过程始于分子内氢键，随后发生在分子间氢键中。已计算出所研究体系及其氘代类似物HOOC-CH═CH-COOD和DOOC-CH═CH-COOD的振动光谱，并与实验数据进行了比较。
