Smearing methods have been used to compute temperature-dependent phonon dispersions and predict critical temperatures of charge density waves,but usually lead to a much higher result because of its ambiguousmechanism ...Smearing methods have been used to compute temperature-dependent phonon dispersions and predict critical temperatures of charge density waves,but usually lead to a much higher result because of its ambiguousmechanism for modeling temperature effects.Here,a three-temperaturemodel was developed to describe the energy transfer process between electrons,soft-mode and non-soft-mode phonons.In particular,mode-selective smearing induced soft-mode phonons were assigned a temperature to analyze its contributions to the relaxation between electrons and phonons.A relative standard was established to screen soft-mode phonons quantitatively for different materials.In addition,three smearing methods(Fermi–Dirac,Gaussian,and Methfessel–Paxton)and eight materials(monolayer or bulk TX_(2),T=Ti,Nb,Ta and X=Se,S)were tested.Critical temperatures corrected by the three-temperature model were in great agreement with experimental results.This work provides new insights into correctly predicting critical temperatures of charge density waves,addressing the relaxation process of electrons and phonons using smearing method and determining phase transitions by phonon softening.展开更多
基金supported by the Guangdong Special Support Program(Grant No.2021TQ06C953)the Shenzhen Science and Technology Programs(Grant No.JCYJ20241202123506009 and GXWD20220811164433002).
文摘Smearing methods have been used to compute temperature-dependent phonon dispersions and predict critical temperatures of charge density waves,but usually lead to a much higher result because of its ambiguousmechanism for modeling temperature effects.Here,a three-temperaturemodel was developed to describe the energy transfer process between electrons,soft-mode and non-soft-mode phonons.In particular,mode-selective smearing induced soft-mode phonons were assigned a temperature to analyze its contributions to the relaxation between electrons and phonons.A relative standard was established to screen soft-mode phonons quantitatively for different materials.In addition,three smearing methods(Fermi–Dirac,Gaussian,and Methfessel–Paxton)and eight materials(monolayer or bulk TX_(2),T=Ti,Nb,Ta and X=Se,S)were tested.Critical temperatures corrected by the three-temperature model were in great agreement with experimental results.This work provides new insights into correctly predicting critical temperatures of charge density waves,addressing the relaxation process of electrons and phonons using smearing method and determining phase transitions by phonon softening.
