We present an extension of our semiempirical floating occupation MO-CI approach for the determination of ground and excited state potential energy surfaces of interest in photochemistry. The QM/MM variant of the method, which allows for electrostatic and van der Waals interactions between the QM and MM subsystems, is supplemented with a treatment of covalent interactions based on Antes and Thiel's connection atom approach. We concentrate on the transferability of the connection atom parameters and on the correct treatment of electrostatic interactions concerning the connection atom itself. We show the viability of the method with three examples of connection atoms: S in a thioether bridge, C and N in a peptide. The results obtained with the QM/MM treatment compare well with all-QM results of the same level.
QM/MM connection atoms for the multistate treatment of organic and biological molecules
GRANUCCI, GIOVANNI;PERSICO, MAURIZIO
2004-01-01
Abstract
We present an extension of our semiempirical floating occupation MO-CI approach for the determination of ground and excited state potential energy surfaces of interest in photochemistry. The QM/MM variant of the method, which allows for electrostatic and van der Waals interactions between the QM and MM subsystems, is supplemented with a treatment of covalent interactions based on Antes and Thiel's connection atom approach. We concentrate on the transferability of the connection atom parameters and on the correct treatment of electrostatic interactions concerning the connection atom itself. We show the viability of the method with three examples of connection atoms: S in a thioether bridge, C and N in a peptide. The results obtained with the QM/MM treatment compare well with all-QM results of the same level.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
