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高压下钙钛矿结构MgSiO3的分子动力学研究 总被引:1,自引:0,他引:1
利用分子动力学方法,研究了高温高压下钙钛矿结构MgSiO3的状态方程.研究表明,分子动力学模拟结果很好地再现了广泛温度和压强范围内钙钛矿结构MgSiO3的摩尔体积.温度300 K压强上升到120 GPa模拟的钙钛矿结构MgSiO3状态方程和有效的实验结果基本一致.在更高温度和更高压强下模拟的钙钛矿结构MgSiO3状态方程和他人的计算值吻合的很好.另外,还分别计算了温度300 K,900 K,1500 K和2500 K压强上升到120 GPa时MgSiO3的体积压缩率. 相似文献
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利用分子动力学方法,研究了高温高压下钙钛矿结构MgSiO_3的状态方程。研究表明,分子动力学模拟结果精确地再现了广泛温度和压强范围内MgSiO_3的摩尔体积。在300 K压强上升到140 GPa模拟的MgSiO_3状态方程和有效的实验值、他人的拟合值以及基于局域密度近似的第一原理计算结果基本一致。并且更高温度和更高压强下模拟的MgSiO_3状态方程和他人的计算值吻合的很好。另外,还分别计算了300、900、2000和3000 K压强上升到120 GPa时MgSiO_3的体积压缩率。 相似文献
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本文采用第一性原理方法,计算了MgSiO3钙钛矿在零温和0 ~ 150 GPa静水压范围内的晶体结构和弹性模量,并利用准简谐近似Debye模型,拟合三阶Birch-Murnaghan物态方程得到了其高温高压下的热力学性质。通过与现有的理论和实验的结果数据比较,确认在0 ~ 2000 K的温度区间内,第一性原理计算结合Debye模型能够较可靠地模拟在下地幔压力范围内MgSiO3钙钛矿的热力学性质。 相似文献
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利用壳层分子动力学方法结合有效的对势,研究了高压条件下CaO的熔化曲线。研究表明,分子动力学模拟结果精确地再现了广泛压强范围内CaO的状态方程。研究中考虑了分子动力学模拟熔化存在的过热现象,通过晶体的现代熔化理论,对CaO的分子动力学模拟熔化温度进行了修正,获得了高温高压下CaO正确的熔化温度。因此,常压下引入壳层模型的分子动力学为研究物质熔化提供了一个很好的方法,这种方法可进一步推广到其它物质的高压熔化研究中。 相似文献
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基于高温高压下面心立方(FCC)铁的状态方程和熔化温度实验数据,建立了热力学模型计算FCC铁、固-液混合相、液态铁在高温高压下的状态方程.在相同密度和温度下,计算的FCC铁、固-液混合铁、液态铁的压强与实验测量结果较为一致,且计算结果与实验结果平均偏差分别为-1.61 GPa、1.05 GPa、-0.05 GPa.在0~100 GPa压强范围内,当铁完全发生熔化时,随着压强的增大其密度变化由-7.5%下降至2.7%. 相似文献
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基于第一性原理分子动力学方法,计算了MgSiO3熔体在0~144GPa、2 000~6 000K的微观结构及其随压力、温度的变化特征。计算的近零压2 000K下O—Si、O—Mg和O—O对分布函数的第一峰值位置分别为0.163 5、0.197 0和0.269 5nm,与实验结果吻合很好。随着压力和温度的变化,MgSiO3熔体结构发生了显著变化,尤其是随着压力增加,结构变得更致密;当密度为4.59g/cm3时,原子间的平均键长随温度(小于5 000K)增加而减小,在常压和更高的压力下,原子间的平均键长随温度变化不明显。在133GPa、4 000K条件下,MgSiO3熔体的O—Si、O—Mg和O—O平均键长分别为0.161 0、0.183 5和0.230 0nm;从地表常压到核幔边界压力,平均Si—O配位数从4变到6,桥氧数目比例由31.3%增高到72.9%。MgSiO3熔体微观结构的认识对了解地幔内硅酸盐流体性质及其对地幔动力学的影响有重要意义。 相似文献
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Belonoshko AB Skorodumova NV Rosengren A Ahuja R Johansson B Burakovsky L Preston DL 《Physical review letters》2005,94(19):195701
The melting curve of MgSiO(3) perovskite has been determined by means of ab initio molecular dynamics complemented by effective pair potentials, and a new phenomenological model of melting. Using first principles ground state calculations, we find that the MgSiO(3) perovskite phase transforms into post perovskite at pressures above 100 GPa, in agreement with recent theoretical and experimental studies. We find that the melting curve of MgSiO(3), being very steep at pressures below 60 GPa, rapidly flattens on increasing pressure. The experimental controversy on the melting of the MgSiO(3) perovskite at high pressures is resolved, confirming the data by Zerr and Boehler. 相似文献
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The melting curve of MgSiO分子动力学 MgSiO3钙钛矿 熔化温度 高压 melting temperature, molecular dynamics, high pressure Project supported by the National Natural Science Foundation of China (Grant Nos 10274055 and 10376021),the Natural Science Foundation of Gansu Province, China (Grant No 3ZS051-A25-027) and the Scientific Research Foundation of Education Bureau of Gansu Province, China (Grant No 0410-01). 2005-01-12 5/8/2005 12:00:00 AM The melting curve of MgSiO3 perovskite is simulated using molecular dynamics simulations method at high pressure. It is shown that the simulated equation of state of MgSiO3 perovskite is very successful in reproducing accurately the experimental data. The pressure dependence of the simulated melting temperature of MgSiO3 perovskite reproduces the stability of the orthorhombic perovskite phase up to high pressure of 130GPa at ambient temperature, consistent with the theoretical data of the other calculations. It is shown that its transformation to the cubic phase and melting at high pressure and high temperature are in agreement with recent experiments. 相似文献
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Zi-Jiang Liu Jun Yan Su-Qing Duan Xiao-Wei Sun Cai-Rong Zhang Yuan Guo 《Solid State Communications》2010,150(13-14):590-593
The high pressure melting curve of CaSiO3 perovskite is simulated by using the constant temperature and pressure molecular dynamics method combined with effective pair potentials for the first time. The simulated results for the partial radial distribution function all compare well with experiment. The calculated equation of state is very successful in accurately reproducing the recent experimental data over a wide pressure range. The predicted high pressure melting curve is in good agreement with the experimental ones, and the melting curve up to the core–mantle boundary pressure, being very steep at lower pressures, rapidly flattens on increasing pressure. The present results also suggest the validity of the experimental data of Zerr and Boehler. 相似文献
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X.W. Sun T. Song Y.D. Chu Z.J. Liu Z.R. Zhang Q.F. Chen 《Solid State Communications》2010,150(37-38):1785-1788
Shell-model molecular dynamics simulation has been performed to investigate the melting of the major Earth-forming mineral CaO at elevated temperatures and high pressures, based on thermal instability analysis. The interatomic potential is taken to be the sum of effective pair-wise additive Coulomb, van der Waals attraction, and repulsive interactions. It is shown that the simulated molar volume of CaO is successful in reproducing recent experimental data and our DFT-GGA calculations up to the core–mantle boundary pressure of 135 GPa. The pressure dependence of the simulated high pressure melting temperature of CaO is in good agreement with the results obtained from the Lindemann melting equation at a pressure of below 7 GPa. The extrapolated melting temperatures are in good agreement with the results obtained from Wang’s empirical model up to 60 GPa. The predicted high pressure melting curve, being very steep at lower pressures, rapidly flattens on increasing pressure. The thermodynamic properties of the rocksalt phase of CaO are summarized in the 0–135 GPa pressure range and for temperatures up to 9300 K. 相似文献
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Xiaowei Sun Qifeng Chen Yandong Chu Chengwei Wang 《Physica B: Condensed Matter》2005,370(1-4):186-194
Shell-model molecular dynamics (MD) simulation has been performed to investigate the melting of the major Earth-forming mineral: periclase (MgO), at elevated temperatures and high pressures, based on the thermal instability analysis. The interatomic potential is taken to be the sum of pair-wise additive Coulomb, van der Waals attraction, and repulsive interactions. The MD simulation with selected Lewis–Catlow (LC) potential parameters is found to be very successful in describing the melting behavior for MgO, by taking account of the overheating of a crystalline solid at ambient pressure. The thermodynamic melting curve is estimated on the basis of the thermal instability MD simulations and compared with the available experimental data and other theoretical results in the pressure ranges 0–150 GPa. Our simulated melting curve of MgO is consistent with results obtained from Lindemann melting equation and two-phase simulated data at constant pressure by Belonoshko and Dubrovinsky, in the pressure below 20 GPa. The extrapolated melting temperatures in the lower mantle are in good agreement with the results obtained from Wang's empirical model up to 100 GPa. Compared with experimental measurements, our results are substantially higher than that determined by Zerr and Boehler, and the discrepancy between DAC and MD melting temperatures may be well explained with different melting mechanisms. Meanwhile, the radial distribution functions (RDFs) of Mg–Mg, O–Mg, and O–O ion pairs near the melting temperature have been investigated. 相似文献
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本文采用第一性原理方法,计算了MgSiO_3钙钛矿在零温和0~150 GPa静水压范围内的晶体结构和弹性模量,并利用准简谐近似Debye模型,拟合三阶Birch-Murnaghan物态方程得到了其高温高压下的热力学性质.通过与现有的理论和实验的结果数据比较,确认在0~2000 K的温度区间内,第一性原理计算结合Debye模型能够较可靠地模拟在下地幔压力范围内MgSiO_3钙钛矿的热力学性质. 相似文献