QMC and phonon study of super-hard cubic boron carbon nitride
QMC and phonon study of super-hard cubic boron carbon nitride
复制标题
DOI：
10.1088/2053-1591/2/10/105902
复制
发表时间：
2015-10
影响因子：
2.3
通讯作者：
M. O. Atambo;N. Makau;G. Amolo;R. Maezono
中科院分区：
文献类型：
--
作者：
M. O. Atambo;N. Makau;G. Amolo;R. Maezono
在这项研究中，我们将声子和量子蒙特卡罗（QMC）计算应用于c-BC 2N，它是通过引入碳从c-BN衍生而来的，以寻找比传统上已知的最硬材料金刚石更便宜和更硬的材料。已经有体积模量的理论密度泛函理论（DFT）结果，其表明c-BC 2N具有比c-BN更高的体积模量。然而，不同的研究小组报告的c-BC 2N的性质的实验数据的不同结果似乎表明了广泛的值。我们发现晶格结构的不稳定性在高压区域的c-BC 2N已被用于体积模量的理论估计。我们还研究了广泛变化的预测取决于在以前的DFT工作中使用的泛函，使用QMC与更准确的处理电子相互作用。考虑到不稳定性，QMC能量-体积拟合仍然发现支持c-BC 2N具有比c-BN更高的体积模量，但与先前理论工作的预测相比差异较小。我们还发现，由于零点振动效应的体积模量大幅减少。
In this study, we have applied phonon and quantum Monte Carlo (QMC) calculations to c-BC2N, which is derived from c-BN by the introduction of carbon, in search of cheaper as well as harder materials that have advantages over the traditionally known hardest material, diamond. There have been theoretical density functional theory (DFT) results of the bulk modulus, which indicate that c-BC2N has a higher bulk modulus than c-BN. However, varied findings of experimental data for the properties of c-BC2N reported by various groups appear to indicate a wide range of values. We found lattice structure instability at the high pressure region of c-BC2N which has been used for theoretical estimations of bulk modulus. We also examined the widely varying predictions depending on the functionals used in previous DFT works, using QMC with a more accurate treatment of the electronic interactions. Taking the instabilities into account, the QMC energy-volume fitting is still found to support that c-BC2N has a higher bulk modulus than c-BN, but with smaller difference than the prediction of the previous theoretical works. We also find substantial reductions in the bulk modulus due to zero point vibrational effects.