[permalink] [id link]

Density functional theory ( DFT ) methods are often considered to be ab initio methods for determining the molecular electronic structure, even though many of the most common functionals use parameters derived from empirical data, or from more complex calculations.

from
Wikipedia

## Some Related Sentences

Density and functional

C < sub > 60 </ sub > with isosurface

**of**ground state electron density as calculated with__Density____functional__**theory**|**DFT**__Density__

__functional__

**theory**

**(**

**DFT**

**)**is a quantum mechanical modelling method used in physics and chemistry

**to**investigate

**the**

**electronic**

**structure**

**(**principally

**the**ground state

**)**

**of**many-body systems

**,**in particular atoms

**,**molecules

**,**and

**the**condensed phases

**.**

* Amsterdam

__Density__Functional**,**a computer program**for**performing density__functional__**theory****electronic****structure****calculations**__Density__

__functional__

**methods**have been applied

**to**investigate

**the**transimination reaction

**,**and

**the**results have shown that

**the**reaction involves three sequential steps:

**(**i

**)**formation

**of**a tetrahedral intermediate with

**the**active site lysine and

**the**amino substrate bonded

**to**

**the**PLP cofactor ;

**(**ii

**)**nondirect proton transfer between

**the**amino substrate and

**the**lysine residue ; and

**(**iii

**)**formation

**of**

**the**external aldimine after

**the**dissociation

**of**

**the**lysine residue

**.**

__Density__

__functional__

**theory**simulations predict that depositing certain adatoms on graphene can render it piezoelectrically responsive

**to**an electric field applied in

**the**vertical

**(**i

**.**e

**.**out-of-plane

**)**direction

**.**

* Point defects in transition metals:

__Density____functional__**theory****calculations**have been performed**to**study**the**systematic trends**of**point defect behaviours in bee transition metals**.**
Recently

**the**DNA fluorescent probe**,**Thiazole Orange**(**TO**)**has been effectively modeled**,**using**the**__Density__Functional Theory**(****DFT****)**with**the**M06-2X__functional__coupled with**the**Polarisable Continuum model**(**PCM**)****.**
Amsterdam

__Density__Functional**(**ADF**)**is a program**for**first-principles**electronic****structure****calculations**that makes**use****of**density__functional__**theory****(****DFT**).

Density and theory

Most quantitative

**calculations**in modern quantum chemistry**use**either valence bond**or****molecular**orbital__theory__as a starting point**,**although a third approach**,**__Density__Functional Theory**,**has become increasingly popular in recent years**.**
* Chemistry: Molecular

__theory__— Kinetic__theory__**of**gases — Molecular orbital__theory__— Valence bond__theory__— Transition state__theory__— RRKM__theory__— Chemical graph__theory__— Flory-Huggins solution__theory__— Marcus__theory__— Lewis__theory__**(**successor**to**Brønsted – Lowry acid – base__theory__**)**— HSAB__theory__— Debye – Hückel__theory__— Thermodynamic__theory__**of**polymer elasticity — Reptation__theory__— Polymer field__theory__— Møller – Plesset perturbation__theory__—__Density__Functional Theory — Frontier**molecular**orbital__theory__— Polyhedral skeletal electron pair__theory__— Baeyer strain__theory__— Quantum__theory__**of**atoms in molecules — Collision__theory__— Ligand field__theory__**(**successor**to**Crystal field__theory__**)**— Variational Transition State Theory — Benson group increment__theory__— Specific ion interaction__theory__

Density and DFT

By 1978 Parr had realized that

__Density__Functional Theory**(**__DFT__**)**would**be**extremely useful in quantitative**calculations****of**chemical and biological systems**,**especially those with high**molecular**weights**.**
In 1989 he and Yang published

__Density__Functional Theory**of**Atoms and Molecules**,**now**considered****the**basic textbook on__DFT__**.**
A book

**,**' The Fundamentals**of**__Density__Functional Theory ' written by H**.**Eschrig**,**contains detailed mathematical discussions on**the**__DFT__; there is a difficulty**for**N-particle system with infinite volume ; however**,**we have no mathematical problems in finite periodic system**(**torus ).
The basic methodology is

__Density__Functional Theory**(**__DFT__), but**the**code also allows**use****of**post-DFT corrections such as hybrid**functionals**mixing__DFT__and Hartree-Fock exchange**,**many-body perturbation**theory****(****the**GW method**)**and dynamical**electronic**correlations within**the**random phase approximation**.**

Density and are

:

__Density__operators__are__those that__are__in**the**closure**of****the**convex hull**of****the**one-dimensional orthogonal projectors**.**
" This variable relation

**of****the**basic motive**of**__Density__21**.**5**to****the**harmonic**structure****of****the**piece**,**and its function in articulating and clarifying**the**formal design**,**__are__exactly what we would expect and take**for**granted in**the**relation between motive and background in traditional tonal music**.**__Density__

**,**Bulk

__Density__

**,**

**or**Wet

__Density__

**,**

**,**

__are__different names

**for**

**the**density

**of**

**the**mixture

**,**i

**.**e.,

**the**total mass

**of**air

**,**water

**,**solids divided by

**the**total volume

**of**air water and solids

**(**

**the**mass

**of**air is assumed

**to**

**be**zero

**for**practical purposes ):

__Density__adjustments at different temperatures

**,**corrections

**for**soda-lime glass expansion and contraction and meniscus corrections

**for**opaque oils

__are__detailed in

**the**Petroleum Measurement Tables

**,**details

**of**usage specified in ASTM D1250

**.**

Most commonly

**,****the**plastic used**to**make bin bags is**the**rather soft and flexible LDPE**(**Low__Density__Polyethylene**)****or****,****for**strength**,**LLDPE**(**Linear Low__Density__Polyethylene**)****or**HDPE**(**High__Density__Polyethylene**)**__are__sometimes used**.**
These may

**be**heuristics-based such as**the**Extended Kalman Filter**or****the**Assumed__Density__Filters described in Peter S**.**Maybeck's book**or****more**methodologically driven such as**the**projection filters introduced by Damiano Brigo**,**Bernard Hanzon and François Le Gland**,**some sub-families**of**which__are__shown**to**coincide with**the**Assumed__Density__Filters**.**
Two examples

**of****the**study**of**sources and sinks__are__Electroencephalography**(**EEG**)**and Current Source__Density__Analysis**(**extracellular field potentials ).

Density and often

Density and be

In " Lisa's Date With

__Density__", Nelson kisses Lisa**,**only**to**__be__berated by Jimbo**,**Kearney**,**and Dolph**,**who believe that kissing girls is " gay "**(**Despite**the**events that occurred revolving around Jimbo in " New Kid On The Block ").
In excited states

**,**chemical reactions**or**when a**more**accurate representation is needed**,****electronic**behavior can__be__obtained**from**first principles by using a quantum mechanical method**,**such as__Density__Functional Theory**.**
At increased

__Density__Altitude**,****for****the**same given indicated airspeed**the**aircraft's true airspeed**(**TAS**)**will__be__higher**,**but**the**same indicated airspeed limits**(**IAS**)**apply**.**__Density__matrices acting on H < sub > A </ sub > only constitute a proper subset

**of**

**the**operators on H < sub > A </ sub > and same can

__be__said

**for**system B

**.**

__Density__altitude is

**the**altitude in

**the**International Standard Atmosphere at which

**the**air density would

__be__equal

**to**

**the**actual air density at

**the**place

**of**observation

**,**

**or**

**,**in other words

**,**

**the**height when measured in terms

**of**

**the**density

**of**

**the**air rather than

**the**distance

**from**

**the**ground

**.**

__Density__Separations may

__be__created by printing three prints

**of**

**the**same picture

**,**each at a different exposure time that will

__be__combined

**for**

**the**final image

**.**

Conversion

**of**Cineon Printing__Density__**(**CPD**)****to**Status-M can__be__estimated with a 3x3 matrix**or**by using tables contained in**the**Kodak " Digital LAD " document**.**
The

**most****common**reliability parameter is**the**mean time**to**failure**(**MTTF ), which can also__be__specified as**the**failure rate**(**this is expressed as a frequency**or**Conditional Probability__Density__Function**(**PDF ))**or****the**number**of**failures during a given period**.**__Density__is desirable as weights must

__be__as small as possible

**,**in order

**to**minimize visual cues which could drive fish away

**from**a fishing operation

**.**

0.169 seconds.