We examine the strain effect on the dielectric permittivity of cubic SrTiO₃ (STO) with Self-Consistent Phonon (SCP) theory calculations. Despite the soft mode frequency overestimation with this theory scheme and workflow, our calculations predict the correct tendency of TO1 with respect to temperature and strain. We found that a uniform tensile strain leads to softer TO1 modes. In addition, the TO1 frequency drops suddenly to zero at a specific temperature in the presence of a ferroelectric transition. The square linear relation between TO1 and temperature is used to estimate the Curie Temperature (T_C), and the STO dielectric permittivity calculated with the Lyddane-Sachs-Teller relation follows the Curie-Weiss (CW) law; which can also be used to determine another T_C value. Results from both approaches are in good agreement with each other and show that T_C increases significantly even when the applied tensile strain is only a few percent.

我们使用自洽声子 (SCP) 理论计算研究了应变对立方 SrTiO ₃ (STO)介电常数的影响。尽管使用此理论方案和工作流程高估了软模式频率，但我们的计算预测了 TO1 相对于温度和应变的正确趋势。我们发现均匀的拉伸应变会导致更软的 TO1 模式。此外，在铁电转变存在的特定温度下，TO1 频率突然下降到零。TO1与温度的平方线性关系用于估计居里温度（T _C），使用Lyddane-Sachs-Teller关系计算的STO介电常数遵循居里-魏斯（CW）定律；也可用于确定另一个 T _C价值。两种方法的结果相互吻合，表明即使施加的拉伸应变只有几个百分点，T _C也会显着增加。