Crystal structure of -nitromethane with atom labels and numbers. The space group is and the unit cell parameters are , , and at 15 K (Ref. 8).
Quantum (solid lines) and classical (dashed lines) , , and values of (a) the C atom and (b) the D(1) atom at temperatures ranging from 4.2 to 150 K. Squares are values, circles are values, and triangles are values.
Plot of (squares), (triangles), and (circles) for the carbon atom in -nitromethane at temperatures from 4.2 to 228 K.
Temperature dependence of (in ) of the O(1) atom in -nitromethane, as determined in PIMD simulations. For comparison, the simple harmonic model of Eq. (11) and the modified harmonic model with effective frequency given by Eq. (12) (the Grüneisen fit) are also shown.
Two-dimensional slice through the numerical PDFs of -nitromethane at 228 K. The fragment is in the plane of the paper, and probability density increases from red to blue.
values (in ) of the D(1) atom in -nitromethane at temperatures between 4.2 and 228 K, as determined in PIMD simulations.
Isosurface of (a) the trivariate Gaussian PDFs and (b) numerical atomic PDFs from the PIMD simulation of -nitromethane at 228 K. The harmonic isosurface is plotted at the 90% probability level. The numerical isosurface has been chosen so that the N-atom isosurfaces are similar in both plots.
PIMD distance corrections (; in pm) to , , and at temperatures between 4.2 and 228 K.
Experimental (Ref. 8) and theoretical ADPs (in ) for -nitromethane at 15 K.
Experimental time-averaged bond lengths (in Å) in nitromethane, , together with the reported TLS corrections and the MD-derived corrections . Note that TLS corrected distances were previously reported to only three decimal places with no uncertainties.
Selected experimental time-averaged bond angles and torsion angles (in degrees) of -nitromethane, together with the experimental equilibrium values determined from the experimental equilibrium structure after applying the PIMD-derived position corrections.
Selected experimental time-averaged intermolecular distances, , for -nitromethane, together with the PIMD-corrected experimental equilibrium values, . All values are given in Å.
Equilibrium bond distances, , obtained by applying the corrections derived from PIMD simulations to the time-averaged experimental structure at 4.2 and 15 K. The bond lengths determined by applying TLS corrections are also shown for comparison. The final two columns show the differences between the final equilibrium bond distances as determined by applying PIMD-derived or TLS corrections. All distances are given in Å.
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