Ab initio quantum chemical calculation of electron density, electrostatic potential, and electric field of biomolecule based on fragment molecular orbital method. Issue 8 (16th November 2017)

• Record Type: Journal Article
• Authors: Ishikawa, Takeshi
• Is Part Of: International journal of quantum chemistry. Volume 118:Issue 8(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-11-16
• Subjects: biomolecule -- electric field -- electrostatic potential -- fragment molecular orbital method -- point charge approximation; Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.25535
• Languages: English
• ISSNs: 0020-7608

Abstract

Abstract: Efficient quantum chemical calculations of electrostatic properties, namely, the electron density (EDN), electrostatic potential (ESP), and electric field (EFL), were performed using the fragment molecular orbital (FMO) method. The numerical errors associated with the FMO scheme were examined at the HF, MP2, and RI‐MP2 levels of theory using 4 small peptides. As a result, the FMO errors in the EDN, ESP, and EFL were significantly smaller than the magnitude of the electron correlation effects, which indicated that the FMO method provides sufficiently accurate values of electrostatic properties. In addition, an attempt to reduce the computational effort was proposed by combining the FMO scheme and a point charge approximation. The error due to this approximation was examined using 2 proteins, prion protein and human immunodeficiency virus type 1 protease. As illustrative examples, the ESP values at the molecular surface of these proteins were calculated at the MP2 level of theory. Abstract : A point charge approximation is combined with the fragment molecular orbital method to reduce the computational effort of quantum chemical calculations of electrostatic properties. This approach allows for the accurate calculations of electrostatic potential values at the molecular surface of the human immunodeficiency virus type 1 protease (3128 atoms) at the MP2 level of theory with cc‐pVDZ basis set.