Cuffari David, Bongiorno Angelo
Department of Chemistry, College of Staten Island, Staten Island, New York 10314, USA.
The Graduate Center of the City University of New York, New York, New York 10016, USA.
Phys Rev Lett. 2020 May 29;124(21):215501. doi: 10.1103/PhysRevLett.124.215501.
A novel method to calculate mode Grüneisen parameters of a material from first principles is presented. This method overcomes the difficulties and limitations of existing approaches, based on the calculation of either third-order force constants or phonon frequencies at different volumes. Our method requires the calculation of phonon frequencies of a material at only the volume of interest, it is based on the second-order differentiation of a corrected stress tensor with respect to normal mode coordinates, and it yields simultaneously all the components of the mode Grüneisen parameters tensor. In this work, after discussing conceptual and technical aspects, the method is applied to silicon, aluminum, scandium fluoride, and a metallic alloy. These calculations show that our method is straightforward and it is suited to be applied to the broad class of materials prone to exhibit structural instabilities, or presenting anisotropy, or chemical and/or structural disorder.
提出了一种从第一性原理计算材料模式格林艾森参数的新方法。该方法克服了现有方法的困难和局限性，现有方法基于三阶力常数或不同体积下声子频率的计算。我们的方法仅需计算材料在感兴趣体积下的声子频率，它基于修正应力张量相对于简正模坐标的二阶微分，并且能同时给出模式格林艾森参数张量的所有分量。在这项工作中，在讨论了概念和技术方面之后，该方法被应用于硅、铝、氟化钪和一种金属合金。这些计算表明，我们的方法很直接，适用于广泛的一类易于表现出结构不稳定性、或呈现各向异性、或存在化学和/或结构无序的材料。
