Fig. 12: Decomposition of the normalized MD displacements with respect to real and imaginary phonon eigenmodes of the cubic conventional unit cell of silicon. | npj Computational Materials

Fig. 12: Decomposition of the normalized MD displacements with respect to real and imaginary phonon eigenmodes of the cubic conventional unit cell of silicon.

From: Scalable machine learning approach to light induced order disorder phase transitions with ab initio accuracy

Fig. 12

The two contributions η real(t) and η imag(t) are defined as in Eqs. (12) and (13), respectively, and represent the modulus of the overlap between the MD normalized trajectory and the phonon eigenvectors of real and imaginary phonon modes, respectively. The MD simulations considered are (a) the 512-atom one and (b) the 1728-atom one at Tl(0) = 0.1 K with the GAP potential for 0.2 photoexcited electrons/holes per Si atom. The overlap is shown for 10 times, ranging between 0 and 1.2 ps, i.e. until both the RMSD and lattice temperature stabilize after non-thermal melting has occurred. Imaginary modes account for 97% and 87% of the MD normalized displacements for t ~ 700 fs, respectively.

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