Density Functional Dependence In The Theoretical Analysis Of The Terahertz Spectrum Of The Illicit Drug MDMA (Ecstasy)

In press, in the IEEE Sensors Journal. This analysis is similar in organization to the HMX and PETN studies published previously but different in scope (not just explosive vs. drug) from these two previous studies because (1) the MDMA molecule is a more flexible system (multiple torsion points not involved in rings), which is of significance because torsional treatments are more sensitive to the prediction of 1-4 electrostatic interactions as a result of the features of the different density functionals and (2) the MDMA.HCl system is a crystal salt, meaning the terahertz (THz) spectrum predictions are expected to have considerable structure originating from ionic motions. And I didn't make the pictures (just saying).


On a slightly lighter note, I have never seen a reviewer's reviewer review quite like this one (the first round of reviews resulted in an extended reply to one reviewer (#2), with another reviewer (#1) then finding it of worth to review the review by this other reviewer).  Anonymity is a beautiful thing sometimes.

Regarding Reviewer 2:  Either he/she A. Did not read the paper, that is only skimmed it, B. Did not understand the paper, or C. Does not know what he/she is talking about.  Reviewer 2's comments were borderline nonsense.

Patrick M. Hakey, Damian G. Allis, Matthew R. Hudson, and Timothy M. Korter

Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA

Abstract: The experimental terahertz (THz) spectrum of the illicit drug 3,4-methylenedioxymethamphetamine hydrochloride (MDMA.HCl, C11H16O2N+.Cl) has been rigorously modeled using solid-state density functional theory (DFT). The compound MDMA.HCl is more widely known by the street name "Ecstasy" and is a commonly abused drug.  The first-principles simulation and assignment of the experimental THz absorption features is a key step in the validation of the spectrum for use in spectral databases for illicit compoundsensing.  This theoretical study includes the use of an array of generalized gradient approximation (GGA) functionals in order to provide a thorough understanding of the performance of the various functionals in the simulation of this crystalline drug. Of the seven studied functionals, the BP functional yielded superior agreement with the experimental data in terms of intramolecular structure and in the position and intensity of spectral features.

Index Terms – Density functional theory, terahertz, MDMA, molecular modeling.

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