Qhov sib txawv tseem ceeb ntawm Born Oppenheimer kwv yees thiab Condon kwv yees yog tias Born Oppenheimer approximation yog qhov tseem ceeb hauv kev piav qhia cov nthwv dej ntawm atomic nuclei thiab electrons hauv cov molecule, whereas Condon approximation yog qhov tseem ceeb hauv kev piav qhia qhov kev siv ntawm vibronic hloov ntawm atoms.
Cov ntsiab lus Yug Oppenheimer kwv yees thiab Condon kwv yees lossis Franck-Condon txoj cai yog cov ntsiab lus tseem ceeb hauv quantum chemistry.
Yug Oppenheimer kwv yees li cas?
Yug Oppenheimer kwv yees yog qhov paub zoo txog kev ua lej nyob hauv molecular dynamics. Lo lus yog siv feem ntau hauv quantum chemistry thiab molecular physics. Nws piav qhia tias nthwv dej ua haujlwm ntawm atomic nuclei thiab electrons hauv ib lub molecule tuaj yeem raug kho nyias nyob ntawm qhov tseeb tias cov nuclei hnyav dua li cov electrons. Txoj kev kwv yees tau muaj npe tom qab Max Born thiab J. Robert Oppenheimer hauv xyoo 1927. Lub hauv paus ntawm qhov kev kwv yees no yog nyob rau lub sijhawm thaum ntxov ntawm quantum mechanics.
Kev kwv yees Born Oppenheimer yog qhov muaj txiaj ntsig hauv quantum chemistry txhawm rau txhawm rau txhawm rau suav cov molecular wavefunctions thiab lwm yam khoom rau cov molecules loj. Txawm li cas los xij, peb tuaj yeem soj ntsuam qee qhov xwm txheej uas qhov kev xav ntawm kev sib cais tsis tau tuav lawm. Qhov no ua rau approximation tsis raug (tseem hu ua kev tawg). Txawm li cas los xij, nws tau siv los ua qhov pib rau lwm txoj hauv kev ua kom zoo.
Hauv thaj teb ntawm molecular spectroscopy, peb tuaj yeem siv Born Oppenheimer kwv yees li qhov suav ntawm cov ntsiab lus ywj pheej ntawm lub zog molecular xws li Etag nrho=Eelectronic+ Evibrational + Enuclear spinFeem ntau, nuclear spin zog yog me me, yog li nws raug tshem tawm los ntawm kev suav. Lub sij hawm hluav taws xob hluav taws xob lossis Ehluav taws xob suav nrog lub zog kinetic, interelectronic repulsions, internuclear repulsions, thiab electron-nuclear attractions, thiab lwm yam.
Feem ntau, Yug Oppenheimer kwv yees zoo li pom qhov sib txawv loj ntawm cov khoom siv hluav taws xob thiab cov loj ntawm atomic nuclei qhov twg lub sij hawm teev ntawm lawv cov lus tsa suab kuj raug txiav txim siab. E.g. ntawm ib tug npaum li cas ntawm kinetic zog, lub nuclei yuav txav qeeb dua cov electrons. Raws li Born Oppenheimer approximation, lub wavefunction ntawm ib tug molecule yog cov khoom ntawm ib tug hluav taws xob wavefunction thiab ib tug nuclear wavefunction.
Condon kwv yees yog dab tsi?
Condon approximation lossis Franck-Condon txoj cai yog txoj cai hauv quantum chemistry thiab spectroscopy uas piav qhia qhov kev siv ntawm vibronic hloov. Peb tuaj yeem txhais cov kev hloov pauv vibronic raws li cov kev hloov pauv ib txhij hauv hluav taws xob thiab kev vibrational zog ntawm cov molecule uas tshwm sim vim qhov nqus los yog emission ntawm photon ntawm lub zog tsim nyog.
Daim duab 01: Daim Duab Zog Raws li Franck-Condon kwv yees
Condon kwv yees hais tias thaum lub sijhawm hloov hluav taws xob uas tshwm sim hauv lub atom, kev hloov pauv ntawm ib qib kev vibrational zog mus rau lwm qib feem ntau tshwm sim yog tias ob lub vibrational yoj ua haujlwm zoo li sib tshooj hauv qhov tseem ceeb.
Txoj ntsiab cai no tau tsim los ntawm James Frack thiab Edward Condon hauv xyoo 1926. Lub hauv paus ntsiab lus no muaj kev txhais lus ib nrab-classical zoo nyob ntawm qhov kev koom tes ntawm cov kws tshawb fawb.
Qhov txawv ntawm Yug Oppenheimer kwv yees thiab Condon kwv yees li cas?
Cov ntsiab lus Yug Oppenheimer kwv yees thiab Condon kwv yees lossis txoj cai Franck-Condon yog cov ntsiab lus tseem ceeb hauv quantum chemistry. Qhov sib txawv tseem ceeb ntawm Born Oppenheimer approximation thiab Condon approximation yog tias Born Oppenheimer approximation yog qhov tseem ceeb hauv kev piav qhia txog nthwv dej ntawm atomic nuclei thiab electrons hauv cov molecule, whereas Condon approximation yog qhov tseem ceeb hauv kev piav qhia qhov kev siv ntawm vibronic hloov ntawm atoms.
Hauv qab no yog cov ntsiab lus ntawm qhov sib txawv ntawm Born Oppenheimer approximation thiab Condon approximation nyob rau hauv daim ntawv teev.
Summary – Yug Oppenheimer kwv yees vs Condon kwv yees
Cov ntsiab lus Yug Oppenheimer kwv yees thiab Condon kwv yees lossis Franck-Condon txoj cai yog cov ntsiab lus tseem ceeb hauv quantum chemistry. Qhov sib txawv tseem ceeb ntawm Born Oppenheimer approximation thiab Condon approximation yog tias Born Oppenheimer approximation yog qhov tseem ceeb hauv kev piav qhia yoj ua haujlwm ntawm atomic nuclei thiab electrons hauv ib lub molecule, whereas Condon approximation yog qhov tseem ceeb hauv kev piav qhia qhov kev siv ntawm vibronic hloov ntawm atoms.
