Scaled quantum mechanical

Yu N, Yennawar H, Merz KM Jr (2005) Refinement of protein crystal structures using energy restraints derived from linear-scaling quantum mechanics. Acta Crystallogr D Biol Crystallogr 61 322-332... 

Alper, J. S., H. Dothe, and M. A. Lowe. 1992. Scaled Quantum Mechanical Calculation of the Vibrational Structure of the Solvated Glycine Zwitterion. Chem. Phys. 161, 199-209. 

Williams, R. W., V. F. Kalasinsky, and A. H. Lowrey. 1993. Scaled Quantum Mechanical Force Field for Cis- and Trans-glycine in Acidic Solution. J. Mol. Struct. (Theochem) 281, 157-171. 

Alper, J. S., H. Dothe, and M. A. Lowe. 1992. Scaled Quantum Mechanical Calculation of the Vibrational Structure of the Solvated Glycine Zwitterion, Chem. Phys. 161, 199-209. Barron, L. D., A. R. Gargaro, L. Hecht, P. L. Polavarapu. 1991. Experimental and Ab Initio Theoretical Vibrational Roman Optical Activity of Alanine, Spectrochimica Acta 47A, 1001-1016. 

Within the framework of the scaled quantum mechanical (SQM) procedure, transferable scaling factors (TSFs) were used to compute the vibrational spectra of dibromofuroxan and diiodofuroxan <2002PCA6810>. 

However, the most reliable and widely used is the method developed by Puley [16], which is now referred to as Scaled Quantum Mechanical Force Field (SQMF). In SQMF a scale constant Xs is ascribed to each internal coordinate qH such that the corrected (scaled) force-constants are calculated according to the equation ... 

Normally the scaling factors are extracted by minimizing the squared deviation (4) considered as a functional R A) of the variable set A, - The frequency parameters z alc now correspond to the harmonic normal frequencies calculated with the scaled quantum-mechanical force-field (6). The first and second derivatives of R( A) with respect to the scaling factors can be calculated analytically [17,18], which permits to implement rapidly converging minimization procedures of the Newton-Gauss type. Alternative iterative minimization methods were also proposed [19]. 

A. Aamouche et al., Neutron inelastic scattering, optical spectroscopies and scaled quantum mechanical force fields for analyzing the vibrational dynamics of pyrimidine nucleic acid bases. 1. Uracil. J. Phys. Chem. 100, 5224-5234 (1996)... 

V. Scaled Quantum Mechanical Force-Field Method.240... 

Scaled quantum-mechanical force fields for furan (and thiophene) and its isotopomers have been calculated with the B3LYP/6-31G method. Corresponding MP2 and FIE calculations gave less satisfactory results. Excellent agreement... 

TABLE 1. Scaled quantum mechanical (SQM) force-field-calculated infrared frequencies (cm ) and intensities (kmmol ) for V(acac)3 and Ti(acac)3. Reproduced with permission from Reference 50... 

Scaled quantum mechanics computations of vibrational spectra of small molecules, including thiirane, were performed by Katsyuba and Vandyukova <2003CPL658>. With 13 scaling factors, applied to B3LYP force fields, they were able to compute stretching and bending frequencies for 26 molecules with a total standatd deviation of about 11 cm for 6-31G and 6-31-l-G basis sets. The latter basis set was recommended for Raman spectra. 

Optimized geometries, scaled quantum-mechanics (SQM) force fields, and the corresponding vibrational frequencies, IR absorption intensities, and scale factors were calculated for thiazole and the [2(2)-H], [4-H-2], and [2,5-H-2(2)] isotopomers of thiazole using the DFT and B3LYB/6-31G methods <1995JCM354, 1995JCM174>. 

White CA, Johnson BG, Gill PMW, Head-Gordon M (1996) Linear scaling density functional calculations via the continuous fast multipole method. Chem Phys Lett 253 268-278 Lee TS, Lewis JP, Yang W (1998) Linear-scaling quantum mechanical calculations of biological molecules the divide-and-conquer approach. Comput Mater Sci 12 259-277 Van Alsenoy C, Yu CH, Peelers A, Martin JML, Schafer L (1998) Ab initio geometry determinations of proteins. 1. Crambin. J Phys Chem A 102 2246-2251... 

A. Aamouche, G. Berthier, C. Coulombeau, J. P. Flament, M. Ghomi, C. Henriet, H. Jobic P.Y. Turpin (1996). Chem. Phys., 204, 353-363. Molecular force fields of uracil and thymine, through neutron inelastic scattering experiments and scaled quantum mechanical calculations. 

Gogonea V, Merz KM. Fully quantum mechanical description of proteins in solution. Combining linear scaling quantum mechanical methodologies with the Poisson-Boltzmann equation. J Phys Chem A 1999 103 5171-5188. 

P. Pulay, G. Fogarasi, G. Pongor, j. E. Boggs, and A. Vargha,/. Am. Chem. Soc., 105, 7037 (1983). Combination of Theoretical Ah Initio and Experimental Information to Obtain Reliable Harmonic Force Constants. Scaled Quantum Mechanical (SQM) Force Fields for Glyoxal, Acrolein, Butadiene, Formaldehyde, and Ethylene. 

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