Data Supporting "Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-Triazine (RDX) Thin Films"

Experimental Data

All data are saved as a .csv file. Each transient .csv file is labeled according to molecule, pump wavelength, file contents, polarization, pump laser power, spectrometer grating position, and a date (e.g. PETN_TA_para_1.8mW_11.1um_06Feb2020.csv). The first column contains frequencies (in cm-1) while the first row indexes each time delay (in ps). Transient spectra at select time delays, i.e. the transient data presented in Figures 4, S10, and S12, are similarly labeled (e.g. PETN_spectra_7.8um_FTIRcorr_07Feb2020.csv) with the same data organization within each file. Select transient spectra shown at 1520 cm-1 (1530 cm-1 pump) or 1330 and 1240 cm-1 (1260 cm-1 pump) regions were taken from the 6.6 µm, 7.5 µm, and 8 µm "TA" datasets respectively. The static RDX FTIR and 33° ThDIR spectra are given as two column .csv files: the first column is frequency (in cm-1) while the second column is either transmission or ΔOD.

Computational Data

Included in the data repository are all of the necessary inputs to perform the vibrational analysis using the Phonopy software package. The minimized PETN crystal used in the finite displacement calculations is given as a POSCAR file format to be used in VASP, the enumeration of all displacements used in the first anharmonic expansion is given in disp_fc3.yaml. The collection of all individual VASP calculations into second- and third-order force constants are contained in the .hdf5 files. The remaining files contain all of the details for the Phonopy calculations done herein, per-mode population adjustments in the JDOS are achieved by modifying the phono3py/phonon3/triplets.py source code file which is distributed with all versions of the code. Additionally, individual normal mode displacements are provided as anime_*.xyz files to be read in by most visualization packages, we have used OVITO. To produce the displacement vector diagrams shown throughout this work, an OVITO scene file (version 3.3+) EigenModeVis_Solid_RDX.ovito has been supplied.

For the MD simulations, the modified interatomic potential and an example LAMMPS input file for a GLE pump-probe simulation are supplied. The structure file of α-RDX has been relaxed at 1 atm of pressure and 300 K given the adjustments made to the N-O, C-H, O-N-O, and H-C-H bond strengths. These adjustments were made based on qualitative agreements between MD and VASP predicted IR spectra, and should not be considered as a general use potential for RDX without further validation.

SAND2023-13312O