Search results for "DFT"

Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems

2020

Over the last few years, extraordinary advances in experimental and theoretical tools have allowed us to monitor and control matter at short time and atomic scales with a high degree of precision. An appealing and challenging route toward engineering materials with tailored properties is to find ways to design or selectively manipulate materials, especially at the quantum level. To this end, having a state-of-the-art ab initio computer simulation tool that enables a reliable and accurate simulation of light-induced changes in the physical and chemical properties of complex systems is of utmost importance. The first principles real-space-based Octopus project was born with that idea in mind,…

Strukturalne i spektroskopowe właściwości wybranych ftalocyjanin

2016

Real-space quantum transport in two-dimensional nanostructures in magnetic fields

2013

Generalized symmetries in nanostructure simulations

2009

Systematic conformational search analysis of the SRR and RRR epimers of 7-hydroxymatairesinol

2010

An extensive and systematic conformational search was performed on the two epimers of the natural lignan 7-hydroxymatairesinol (HMR), by means of a home-made Systematic Conformational Search Analysis (SCSA) code, designed to select more and more stable conformers through sequential geometry optimization of trial structures at increasing levels of calculation theory. In the present case, the starting molecular structures were selected by the semi-empirical AM1 method and filtered – i.e. decreased in number by choosing the more stable species – on the basis of their energy calculated by the HF method and the 6-31G(d) basis set. The geometries obtained were further refined by performing densit…

Synteza i charakterystyka spektralna oktakarboksyftalocyjanin metali

2017

Przedstawiona praca dotyczy metod syntezy oktakarboksyftalocyjanin cynku, glinu i galu oraz ich charakterystyki spektralnej (spektroskopii UV-Vis), którą przestawiono zarówno z punktu widzenia eksperymentalnego, jak i teoretycznego. Opisano istniejące metody syntezy ftalocyjanin i ich modyfikacje prowadzące do uzyskania pochodnych rozpuszczalnych w wodzie, mających jako podstawniki peryferyjne osiem grup karboksylowych. Scharakteryzowano widma absorpcyjne UV- Vis typowe dla ftalocyjanin, dzięki którym można uzyskać wiele cennych informacji na temat tych kompleksów. Ponadto przeprowadzono obliczenia absorpcyjnych widm UV oktakarbosyftalocyjaniny cynku w ramach zależnej od czasu metody funkcj…

Weak Interactions between Trivalent Pnictogen Centers: Computational Analysis of Bonding in Dimers X3E···EX3 (E = Pnictogen, X = Halogen)

2009

The nature of weak interactions in dimers X3E···EX3 (E = N−Bi, X = F−I) was investigated by wave function and density functional theory (DFT)-based methods. Out of the 20 systems studied, 10 are found to be bound at the CP-MP2 and LMP2 levels of theory. Detailed partition of the interaction energy into different components revealed that dispersion is the primary force holding the dimers together but there also exists an important ionic component whose contribution increases with increasing halogen size. As expected, standard density functionals fail to describe bonding in the studied systems. However, the performance of DFT methods can be easily improved via empirical dispersion correction …

New Tetraphosphane Ligands {(X2P)2NC6H4N(PX2)2} (X = Cl, F, OMe, OC6H4OMe-o): Synthesis, Derivatization, Group 10 and 11 Metal Complexes and Catalyti…

2008

The reaction of p-phenylenediamine with excess PCl3 in the presence of pyridine affords p-C6H4[N(PCl2)2]2 (1) in good yield. Fluorination of 1 with SbF3 produces p-C6H4[N(PF2)2]2 (2). The aminotetra(phosphonites) p-C6H4[N{P(OC6H4OMe-o)2}2]2 (3) and p-C6H4[N{P(OMe)2}2]2 (4) have been prepared by reacting 1 with appropriate amount of 2-(methoxy)phenol or methanol, respectively, in the presence of triethylamine. The reactions of 3 and 4 with H2O2, elemental sulfur, or selenium afforded the tetrachalcogenides, p-C6H4[N{P(O)(OC6H4OMe-o)2}2]2 (5), p-C6H4[N{P(S)(OMe)2}2]2 (6), and p-C6H4[N{P(Se)(OMe)2}2]2 (7) in good yield. Reactions of 3 with [M(COD)Cl2] (M = Pd or Pt) (COD = cycloocta-1,5-diene)…

Synthesis, X-Ray Structure, Tautomerism Aspect, and Chemical Insight of The 3-(1H-Indol-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-ol

2021

The 3-(1H-indol-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-ol 2 was obtained exclusively in the enol configuration starting from triazolyl-indole derivative 1 and alkyl halo-esters in the presence of K2CO3. Chemical structure elucidations with the aid of physicochemical characterizations were used to predict its molecular structure while single crystal X-ray diffraction technique was used to shed the light on the supramolecular structure of 2. DFT calculations agreed very well with the reported X-ray structure where the most stable form thermodynamically is the enol form. Its optimized geometry agreed very well with the experimental structure where the correlation coefficients betwe…

An experimental and theoretical study of a heptacoordinated tungsten(VI) complex of a noninnocent phenylenediamine bis(phenolate) ligand

2018

Abstract [W(N2O2)(HN2O2)] (H4N2O2 = N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine) with a noninnocent ligand was formed by reaction of the alkoxide precursor [W(eg)3] (eg = the 1,2-ethanediolate dianion) with two equivalents of ligand. The phenol groups on one of the ligands are completely deprotonated and the ligand coordinates in a tetradentate fashion, whereas the other ligand is tridentate with one phenol having an intact OH group. The molecular structure, magnetic measurements, EPR spectroscopy, and density functional theory calculations indicate that the complex is a stable radical with the odd electron situated on the tridentate amidophenoxide ligand. The formal ox…