Energy Density Material

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1 6F P with 3F 4F P level P to F P level Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics UFirst Principles Prediction of an Insensitive High Energy Density Material USupplemental Information,,* Barak HirshbergP P and Chagit DenekampP. The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Jerusalem, 9904, Israel. RAFAEL Ltd. P.O. Box 50. Haifa 300, Israel. *Corresponding author. U U: Ubarak.hirshberg@mail.huji.ac.ilUT UTelU: +97 (4) UFaxU: +97 (4) Computational details In order to validate our results for the gas phase properties of H3tta, the minimum structure was also located at the MP/cc-pVTZP0F, of theory. The structure obtained is very similar to the one obtained at the B3LYP/6-3G(d)PF 3, 4, 5 of theory (e.g. maximal variation of 0.03 Ǻ in bond lengths). Both structures are given below. Dimer calculations, due to the larger number of heavy atoms, were done using the BLYP functionalp5f 6, 7 the 6-3G(d) basis set. The detonation properties of H3tta were also calculated using the Kamlet-Jacobs methodp7f to the more reliable EXPLO5 results.. Clusters Equilibrium Structure 8 compare The geometry obtained for a dimer of H3tta molecules is shown in Figure.

2 Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics Figure Equilibrium Geometry for the H3tta dimer at the B3LYP/6-3G(d) level of theory The existence of the dimer was used in generating the initial geometry for PW-DFT optimization. The initial unit cell parameters for the P phase were chosen in order to generate a structure of dimers on top of the other, shifted by an angle of approximately 750. The geometry used as initial guess is shown in Figure. Figure Initial geometry for PW-DFT optimization shown in top view (l.h.s) and side view (r.h.s). 3. Kamlet Jecobs method The detonation properties of H3tta were also evaluated using the Kamlet-Jacobs method. This method uses an empirical relation, given in equation (), between detonation velocity (D) or pressure (P) and ρ 0, N, M and Q; where ρ 0 is the density of the solid, N is the number of moles

3 P for P and P and P and P for P for Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics of gas released during detonation, M is the average molecular weight of the gas released and Q is the heat of detonation. This method has been used extensively in the literature for evaluating the performance of possible HEDMs (for recent examples, see ref. 7a and 7b in the main article). () 0 D =.0 ( NM Q P = 5.58 ρ ( NM Q ) ) ( +.3 ρ ) 0 The initial density used in this study is the one obtained from PW-DFT calculations for each of the crystal structures. In order to evaluate N, M and Q the reaction presented in Figure 3 was used. Q is the heat of detonation and is defined as the negative of the difference between the heat of formation of the products and the heat of formation of the explosive. This procedure resulted in values of mole gp molep P, g N and M, respectively. The effect of variation in the solid state heat of formation of each phase on the detonation properties was also tested. Q was found to be between 9 cal gp P phase and between 3 cal gp cal gp 8 cal gp the the PRR phase. The values of D and P obtained, using equation (), for the P phase are msp P and kbar, respectively. For the PRR phase D and P were found to be msp kbar, respectively. These values are in accord with the EXPLO5 results reported in the main article. N N HN N N N 3 N N N H 9N (g) + H (g) + 8C (s) + CH 4(g) + NH 3(g) N N NH N

4 Figure 3 Detonation reaction used to estimate N,M and Q for the Kamlet Jacobs method. 4. Geometries H3tta B3LYP/6-3G(d) E(RB+HF-LYP): Hartree N C C N N N N H N N N N H C N N N N H H3tta MP/cc-pVDZ E(MP): Hartree N C C N N N N H N N N N H C N N N N H H3tta dimer BLYP/6-3G(d) E(RB-LYP): Hartree

5 N N N C H N N C C N N N N N H N N N H N N N C N N H C C N N N N N H N N N H P unit cell geometry total energy = Ry N C C N N N N H N N N N H C N N N

6 N H N C C N N N N H N N N N H C N N N N H P unit cell geometry total energy = Ry N N N C H N N C C N N N N N H N N N H N N N C N N H C C N N N N N H N N

7 N H IR Spectrum P Phase # mode [cm] [THz] IR

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9 P Phase # mode [cm] [THz] IR

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11 C. Møller and M.S. Plesset Phys. Rev. 934, 46, T.H. Dunning Jr. J. Chem. Phys. 989, 90, A.D. Becke J. Chem. Phys. 993, 98, P.C. Hariharan and J.A. Pople Theor. Chim. Acta 973, 8, P.J. Stephens, F.J. Devlin, C.F. Chabalowski and M.J. Frisch J. Phys. Chem. 994, 98, A.D. Becke Phys. Rev. A 988, 38, C. Lee, W. Yang and R.G. Parr Phys. Rev. B 988, 37, M.J. Kamlet and S.J. Jacobs J. Chem. Phys. 968, 48, 3-35.