As electronic devices become increasingly miniaturized, heat management at the nanoscale emerges as a challenge, especially for devices operating in sub-microns. Traditional heat conduction models fail to capture the complex behavior of thermal transfer at this scale, where phonons—vibrational energy carriers in the lattice structure—dominate.

In particular, there are two key obstacles to address in phonon-based heat simulation. One is the reliance on empirical parameters, which limits the model's adaptability across different materials, while the other is the enormous computational resources required for three-dimensional (3D) simulations.

In a study published by a team of researchers from Shanghai Jiaotong University, led by thermophysics professor Hua Bao, a novel computational method addressing these challenges is reported. The work is published in the journal Fundamental Research.

"When device sizes shrink to scales comparable to the phonon mean free path, the classical Fourier law no longer applies," explains Bao. "To model heat conduction accurately, we must use the phonon Boltzmann transport equation (BTE). That said, solving this equation efficiently for 3D structures has been a challenge."

Nonetheless, by applying Fermi's golden rule to precisely calculate the necessary parameters from first principles, the team successfully eliminated the need for empirical parameters. This breakthrough allows the model to be applied across a wide range of materials while maintaining high accuracy.

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