ΚΒΑΝΤΟΜΗΧΑΝΙΚΟΙ ΥΠΟΛΟΓΙΣΜΟΙ ΤΩΝ ΗΛΕΚΤΡΙΚΩΝ ΠΟΛΩΣΙΜΟΤΗΤΩΝ ΚΑΙ ΥΠΕΡΠΟΛΩΣΙΜΟΤΗΤΩΝ ΜΕΡΙΚΩΝ ΟΡΓΑΝΙΚΩΝ ΜΟΡΙΩΝ ΚΑΙ ΑΝΙΟΝΤΩΝ

1984 ◽  
Author(s):  
John Waite
Keyword(s):  
Basis Set ◽  
Hartree Fock

ΠΑΡΟΥΣΙΑΖΕΤΑΙ ΜΙΑ ΜΕΘΟΔΟΣ ΓΙΑ ΤΟΝ ΥΠΟΛΟΓΙΣΜΟ ΤΗΣ ΜΕΣΗΣ ΗΛΕΚΤΡΙΚΗΣ ΠΟΛΩΣΙΜΟΤΗΤΑΣΑ, ΚΑΙ ΤΩΝ ΥΠΕΡΠΟΛΩΣΙΜΟΤΗΤΩΝ Β ΚΑΙ Γ ΟΡΓΑΝΙΚΩΝ ΜΟΡΙΩΝ. Η ΜΕΘΟΔΟΣ ΑΥΤΗ ΣΤΗΡΙΖΕΤΑΙ ΣΕ ΜΙΑ ΗΜΙΕΜΠΕΙΡΙΚΗ ΚΥΜΑΤΟΣΥΝΑΡΤΗΣΗ (CNDO), Η ΟΠΟΙΑ ΠΡΟΣΔΙΟΡΙΖΕΤΑΙ ΜΕ ΤΗΝ ΒΟΗΘΕΙΑ ΜΙΑΣ ΜΙΚΡΗΣ ΒΑΣΗΣ (BASIS SET) ΠΡΟΣΕΚΤΙΚΑ ΕΠΙΛΕΓΜΕΝΗΣ. Η ΚΥΜΑΤΟΣΥΝΑΡΤΗΣΗ ΔΙΑΤΑΡΑΣΣΕΤΑΙ ΚΑΤΑ ΤΟΝ ΤΡΟΠΟ ΠΟΥ ΟΡΙΖΕΙ Η ΘΕΩΡΙΑ COUPLED HARTREE- FOCK. Η ΘΕΩΡΙΑ ΧΡΗΣΙΜΟΠΟΙΗΘΗΚΕ ΚΑΤΑ ΤΗΝ ΜΟΡΦΗ ΠΟΥ ΠΡΟΤΑΘΗΚΕ ΑΠΟ ΤΟΝ MCWEENY ΚΑΙ ΤΟΥΣ ΣΥΝΕΡΓΑΤΕΣ ΤΟΥ. Η ΣΥΓΚΕΚΡΙΜΕΝΗ ΤΕΧΝΙΚΗ ΥΠΟΛΟΓΙΣΜΟΥ ΤΩΝ Α,Β ΚΑΙ Γ ΔΙΑΜΟΡΦΩΘΗΚΕ ΥΣΤΕΡΑ ΑΠΟ ΜΕΛΕΤΗ ΠΟΛΛΩΝ ΕΝΑΛΛΑΚΤΙΚΩΝ ΛΥΣΕΩΝ. (ΠΕΡΙΚΟΠΗ)

Ab initio predictions of the zero field splittings and the singlet–triplet transition strengths for the n → π* transition of selenoformaldehyde

1993 ◽  
Vol 71 (10) ◽  
pp. 1706-1712 ◽  
Author(s):  
D.C. Moule ◽  
L. Chantranupong ◽  
R.H. Judge ◽  
D.J. Clouthier
Keyword(s):  
Energy Levels ◽  
Random Phase ◽  
Open Shell ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Hartree Fock ◽  
Lower Valence ◽  
Polarization Functions

The energy levels of the lower valence and Rydberg states of selenoformaldehyde, CH2Se, have been calculated by the SCF/CI method. Wavefunctions for the ROHF (restricted open shell Hartree–Fock) states were obtained with the Binnings–Curtis double-ζ basis set, augmented with Rydberg and polarization functions. Configuration interaction was applied to the parent configurations, PCMO (parent configuration molecular orbital). Oscillator strengths were evaluated for the allowed electric dipole transitions by the RPA (random phase approximation), and SOPPA (second-order polarization propagator approximation) methods. The spin-orbit contribution to the zero field splitting of the first triplet state, 3A2(n,π*) as well as the oscillator strengths to the three spin components were calculated by perturbation theory. These calculations predict that the Sx, Sy, and Sz components are shifted by −96.091,−96.707, and + 29.167 cm−1, respectively, from their unperturbed position. The oscillator strengths for the three components fx, fy, and fz of the 3A2(n,π*) ← 1A1(g.s.) transition were calculated to be 3.45 × 10−7, 1.15 × 10−7, and 173.0 × 10−7.

scholarly journals Optical Properties of Silver-Mediated DNA from Molecular Dynamics and Time Dependent Density Functional Theory

2018 ◽  
Vol 19 (8) ◽  
pp. 2346 ◽  
Author(s):  
Esko Makkonen ◽  
Patrick Rinke ◽  
Olga Lopez-Acevedo ◽  
Xi Chen
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Time Dependent ◽  
Basis Set ◽  
Dna Nanostructures ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Spurious Peak ◽  
20 Nm ◽  
Dependent Density

We report a combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics and time-dependent density functional (TDDFT) study of metal-mediated deoxyribonucleic acid (M-DNA) nanostructures. For the Ag + -mediated guanine tetramer, we found the maug-cc-pvdz basis set to be sufficient for calculating electronic circular dichroism (ECD) spectra. Our calculations further show that the B3LYP, CAM-B3LYP, B3LYP*, and PBE exchange-correlation functionals are all able to predict negative peaks in the measured ECD spectra within a 20 nm range. However, a spurious positive peak is present in the CAM-B3LYP ECD spectra. We trace the origins of this spurious peak and find that is likely due to the sensitivity of silver atoms to the amount of Hartree–Fock exchange in the exchange-correlation functional. Our presented approach provides guidance for future computational investigations of other Ag + -mediated DNA species.

Performance of small basis set Hartree–Fock methods for modeling non-covalent interactions

2021 ◽  
Vol 3 (3) ◽  
pp. 034007
Author(s):  
Viki Kumar Prasad ◽  
Alberto Otero-de-la-Roza ◽  
Gino A DiLabio
Keyword(s):  
Basis Set ◽  
Hartree Fock ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Basis-Set Expansions of Relativistic Electronic Wave Functions

2007 ◽  
Author(s):  
Kenneth G. Dyall ◽  
Knut Faegri
Keyword(s):  
Relativistic Quantum ◽  
Finite Basis ◽  
Wave Functions ◽  
Basis Set ◽  
Electronic Wave ◽  
Nonrelativistic Case ◽  
Hartree Fock ◽  
Electronic Wave Functions ◽  
Basis Set Expansion ◽  
Molecular Calculations

There have been several successful applications of the Dirac–Hartree–Fock (DHF) equations to the calculation of numerical electronic wave functions for diatomic molecules (Laaksonen and Grant 1984a, 1984b, Sundholm 1988, 1994, Kullie et al. 1999). However, the use of numerical techniques in relativistic molecular calculations encounters the same difficulties as in the nonrelativistic case, and to proceed to general applications beyond simple diatomic and linear molecules it is necessary to resort to an analytic approximation using a basis set expansion of the wave function. The techniques for such calculations may to a large extent be based on the methods developed for nonrelativistic calculations, but it turns out that the transfer of these methods to the relativistic case requires special considerations. These considerations, as well as the development of the finite basis versions of both the Dirac and DHF equations, form the subject of the present chapter. In particular, in the early days of relativistic quantum chemistry, attempts to solve the DHF equations in a basis set expansion sometimes led to unexpected results. One of the problems was that some calculations did not tend to the correct nonrelativistic limit. Subsequent investigations revealed that this was caused by inconsistencies in the choice of basis set for the small-component space, and some basic principles of basisset selection for relativistic calculations were established. The variational stability of the DHF equations in a finite basis has also been a subject of debate. As we show in this chapter, it is possible to establish lower variational bounds, thus ensuring that the iterative solution of the DHF equations does not collapse. There are two basically different strategies that may be followed when developing a finite basis formulation for relativistic molecular calculations. One possibility is to expand the large and small components of the 4-spinor in a basis of 2-spinors. The alternative is to expand each of the scalar components of the 4-spinor in a scalar basis. Both approaches have their advantages and disadvantages, though the latter approach is obviously the easier one for adapting nonrelativistic methods, which work in real scalar arithmetic.

Electric Quadrupole Moment of the 14N Nucleus Determined by ab initio Cl Calculation on NH3

1986 ◽  
Vol 41 (1-2) ◽  
pp. 163-165 ◽  
Author(s):  
Tae-Kyu Ha
Keyword(s):  
Electric Field Gradient ◽  
Ab Initio ◽  
Electric Quadrupole ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Electric Quadrupole Moment ◽  
Coupling Constant ◽  
Hartree Fock ◽  
Quadrupole Coupling ◽  
Constant E

Based on the calculated electric field gradient (q) from ab initio Cl wavefunctions with largebasis set (including ƒ functions on N and d functions on H) and the experimental nuclearquadrupole coupling constant (e Q q) for nitrogen in NH3, an improved value o f the quadrupole moment of 14N is proposed as Q (14N ) = 2.08 x 10-26cm2. The value calculated using a wavefunctionnear the Hartree-Fock limit enlarged ≈ 10% by the Cl treatment.

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