The Microcanonically Optimized Transmission Coefficient

It has been shown that the pOMT transmission coefficients are comparable in accuracy with the LAT transmission coefficients for atom-diatom reac-tions. Often we just say OMT without including the microcanonical specification in the algorithm (OMT can also mean canonical OMT in which we first thermally average the SCT and LCT probabilities and then choose the larger transmission coefficient). The resulting VTST/OMT rate constants 

Sometimes we just say VTST/MT. The MT acronym ( multi-dimensional tunneling ) can denote ZCT, SCT, LCT, or OMT, all of which are multidimensional, but we usually use SCT or OMT when we carry out MT calculations. 

Achieving chemical accuracy by electronic structure calculations is computationally expensive, and the time required calculating a rate constant is governed almost entirely by the time spent calculating the gradients and Hessians. In addition, the accuracy of the rate constant depends on the accuracy of the electronic structure method. Therefore, the user must make judicious decisions about the length of the MEP, how often Hessians are calculated, whether to use options like LCT that require extra information about the PES, and which electronic structure method to use. 

Direct dynamics calculations can be carried out by interfacing an electronic structure package with POLYRATE, and several such interfaces are available, including GAUSSRATE, GAMESSPLUSRATE,  

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