Validation of Numerical Multicenter Integration Schemes for Large Scale Density Functional Calculation

Abstract

Large-scale density functional (DF) calculations were made possible by both high-performance computers and an efficient quantum chemical calculation algorithm. The exchange correlation (XC) term in the DF calculation is generally estimated by numerical integral scheme, and the accuracy and computational complexity depends on the combination of the various methods. Even though the accurate scheme is proposed for small molecules, the effectiveness is not verified enough for large-scale molecules. For the analysis of molecular properties such as chemical reaction, vibration spectrum, and so on, the integral scheme is demanded on 0.01~0.1 kcal/mol accuracy. The larger the molecule size is, the more the number of significant figures may be needed. In addition, not only the accuracy but also the feasibility is important for large-scale calculations. It is necessary to evaluate the balance of the accuracy and the computational complexity. In this study, we carried out large-scale DF calculations by using various numerical integral methods to estimate XC term and investigated these schemes and the feasibility.