The question of how density functional theory (DFT) compares with Hartree-Fock (HF) for the computation of momentum-space properties is addressed in relation to systems for which (near) exact Kohn-Sham (KS) and HF one-electron matrices are known. This makes it possible to objectively compare HF and exact KS and hence to assess the potential of DFT for momentum-space studies. The systems conside...

In a previous study we reported an efficient, accurate multiresolution solver for the Kohn-Sham self-consisitent field (KS-SCF) method for general polyatomic molecules. This study presents an efficient numerical algorithm to evalute Hartree-Fock (HF) exchange in the multiresolution SCF method to solve the HF equations. The algorithm employs fast integral convolution with the Poission kernel in ...

Internal rotations of the methyl group in ortho-substituted and 2,6-disubstituted toluenes in their ground state have been investigated by means of various ab initio quantum chemistry methods. Computed barriers at the Hartree-Fock (HF) level using medium sized basis sets agreed reasonably with experimental results in the case of the studied ortho-substituted toluenes. However, this agreement wo...

Our gargantuan ab initio all-electron fully relativistic Dirac–Fock (DF), nonrelativistic (NR) Hartree–Fock (HF) and Dirac–Fock-Breit-Gaunt (DFBG) molecular SCF calculations for the superheavy octahedral oganesson hexatenniside OgTs6 predict atomization energies (AEs) of 9.49, −5.54 9.37 eV, at optimized Og-Ts bond distances 3.35, 3.44 3.36 Å, respectively. There are dramatic effects relativity...

the interaction of dopamine and cysteine for formation of 5-s-cysteinyldopamine are investigated at thehartree-fock level theory. the structural and vibrational properties of 5-s-cysteinyldopamine are studiedat level of hf/6-31g*.interaction energy ( ae) is calculated -771.6923 kcal/mol rotational energy andthermodynamic parameters around two bond have been determined using hf/3-21g. changes of...

We describe perturbative methods for improving finite-basis Hartree-Fock calculations toward the complete-basis limit. The best method appears to offer quadratic error reduction and preliminary numerical applications demonstrate that remarkably accurate Hartree-Fock energies can be obtained.

This work expands the results and derivations presented in a recent letter. It is argued that symmetry breaking Hartree-Fock (HF) solutions of a simple model of the Cu-O planes in La2CuO4, are able to describe the insulator and antiferromagnetic characters of this material. Then, this classical primer of a Mott insulator is alternatively obtained here as an exact Slater insulator within the sim...

Hartree-Fock (HF) theory is most often applied to study the electronic ground states of molecular systems. However, with the advent of numerical techniques for locating higher solutions of the self-consistent field equations, it is now possible to examine the extent to which such mean-field solutions are useful approximations to electronic excited states. In this Communication, we use the maxim...

The problem of electron motion in an arbitrary field of nuclei is an important quantum mechanical problem finding applications in many diverse fields. From the variational principle we derive a procedure, called the Hartree-Fock (HF) approximation, to obtain the many-particle wavefunction describing such a system. Here, the central physical concept is that of electron indistinguishability: whil...

Using ab initio unrestricted Hartree−Fock, restricted open-shell Hartree−Fock, and fourth-order perturbation theory methods, 13 minima on the Si2CH4+ potential energy surface have been calculated including ion−molecule complexes, Si−H and C−H insertion products, and other Si2CH4+ isomers. The transition states connecting those isomers have been located and the minimum energy paths have been tra...