Full geometry optimizations using the PM3, AMl, 3-21G*/HF and 6-31G*/HF levels of theory were conducted on the syn and anti conformations of cyclic 3’,5’-adenosine monophosphate (CAMP). Comparison of the anti crystal structures with the semiempirical and ab initio results revealed that the ab initio results agree well with the experimental results. The results of semiempirical calculations are ...

Several semiempirical methods were utilized to analyze the structures and stabilities of X(H2O)n (X = F, Cl; n = 1–4) clusters with respect to the number of water molecules through their comparison with ab initio molecular orbital calculations. Our results show that the recently developed PM6-DH+ semiempirical method can provide reasonable binding energies of hydrated fluoride and chloride ion ...

Density-functional and semiempirical quantum methods and continuum dielectric and explicit solvation models are applied to study the role of solvation on the stabilization of native and thio-substituted transphosphorylation reactions. Extensive comparison is made between results obtained from the different methods. For the semiempirical methods, explicit solvation was treated using a hybrid qua...

We parametrize a linear-scaling quantum mechanical force field called mDC for the accurate reproduction of nonbonded interactions. We provide a new benchmark database of accurate ab initio interactions between sulfur-containing molecules. A variety of nonbond databases are used to compare the new mDC method with other semiempirical, molecular mechanical, ab initio, and combined semiempirical qu...