Factorial design - principal component regression calculation of fundamental vibrational frequencies

A factorial design-principal component regression method is proposed for ca lculating fundamental vibrational frequencies. The method is illustrated by estimating both observed and anharmonicity-corrected frequencies of CHF3 u sing theoretical frequencies of CH3F, CH2F2 and CHF3 and observed and corre cted frequencies of CH3F and CH2F2 Theoretical frequencies are provided by ab initio molecular orbital calculations prescribed by 2(4-1) fractional fa ctorial designs. The estimated observed and anharmonicity-corrected CHF3 fr equencies are 0.1%-2.8% of the experimental values. These results are much more accurate than those obtained by simple linear regression (0.2%-11.9%) or those of the 2(4-1) factorial design. (C) 1999 Elsevier Science B.V. All rights reserved.