Quantum mechanical ab initio UHF, MP2, MC-SCF and DFT calculations with moderate Gaussian basis sets were performed for MnX6, X = H2O, F, CN, manganese octahedral complexes. The correct spin-state of the complexes was obtained only when the counter ions neutralizing the entire complexes were used in the modelling at the B3LYP level of theory.

Quantum mechanical binding free energies based on thousands of full-protein DFT calculations are tractable, reproducible and converge well.

Density functional theory (DFT) methods for calculating the quantum mechanical ground states of condensed matter systems are now a common and significant component of materials research. The growing importance of DFT reflects the development of sufficiently accurate functionals, efficient algorithms and continuing improvements in computing capabilities. As the materials problems to which DFT is...

Conventional density functional theory (DFT) fails to describe accurately the London dispersion essential for describing molecular interactions in soft matter (biological systems, polymers, nucleic acids) and molecular crystals. This has led to several methods in which atom-dependent potentials are added into the Kohn-Sham DFT energy. Some of these corrections were fitted to accurate quantum me...

The molecular structure of capecitabine (a widely applied prodrug of 5-fluorouracil) was studied by multinuclear NMR measurements and DFT quantum mechanical calculations. One or two tautomeric forms in a solution were detected depending on the solvent used. In the organic solvents, a mixture of two forms of capecitabine was observed: carbamate and imine tautomers. In the aqueous solution, only ...

We evaluate the minimum energy configuration (MM) and binding free energy (QM/MM and QM) of CO2 to Rubisco, of fundamental importance to the carboxylation step of the reaction. Two structural motifs have been used to achieve this goal, one of which starts from the initial X-ray Protein Data Bank structure of Rubisco's active centre (671 atoms), and the other is a simplified, smaller model (77 a...

We rigorously derive an effective quantum mechanical Hamiltonian from N = 4 gauge theory in the BMN limit. Its eigenvalues yield the exact one-loop anomalous dimensions of scalar two-impurity BMN operators for all genera. It is demonstrated that this reformulation vastly simplifies computations. E.g. the known anomalous dimension formula for genus one is reproduced through a one-line calculatio...

The quantum transport computations have been carried on four different width of zigzag graphene using a nonequilibrium Green’s function method combined with density functional theory. The computed properties are included transmittance spectrum, electrical current and quantum conductance at the 0.3V as bias voltage.  The considered systems were composed from one-layer graphene sheets differing w...

Density functional theory (DFT) at the generalised gradient approximation level is employed within the periodic electrostatic embedded cluster method (PEECM) to model the brucite (0001) surface. Three representative studies are then used to demonstrate the reliability of the PEECM for the description of the interactions of various ionic species with the layered Mg(OH)2 structure, and its perfor...

Quantum computing is the field of science that uses quantum-mechanical phenomena, such as superposition and entanglement, to perform operations on data. The fundamental information unit used in quantum computing is the quantum bit or qubit. It is well-known that quantum computers could theoretically be able to solve problems much more quickly than any classical computers. Currently, the first a...