Qhov sib txawv tseem ceeb ntawm ntau qhov sib txawv thiab daim ntawv cog lus yog qhov sib txawv yog hais txog tus naj npawb ntawm qhov ua tau taw qhia ntawm lub zog ntawm qib, qhov kev txiav txim siab yog hais txog qhov ntsuas ntawm tus lej ntawm cov khoom siv hluav taws xob hauv cov khoom siv tshuaj.
Ntau qhov kev txiav txim thiab daim ntawv cog lus yog cov khoom ntawm cov tshuaj sib xyaw. Lub tswv yim ntawm ntau ntau yog ib qho tseem ceeb hauv quantum chemistry, thaum lub tswv yim ntawm daim ntawv cog lus yog qhov tseem ceeb hauv molecular dynamics.
Yuav ua li cas yog Multiplicity?
Multiplicity hais txog tus naj npawb ntawm cov kev taw qhia ua tau ntawm kev tig ntawm lub zog. Lub tswv yim no muaj txiaj ntsig zoo hauv spectroscopy thiab quantum mechanics. Qhov sib npaug rau qhov ntsuas ntawm qhov ntau yog 2S + 1 qhov twg "S" yog hais txog tag nrho cov kiv puag ncig lub zog. Cov txiaj ntsig peb tuaj yeem tau txais rau ntau qhov suav nrog 1, 2, 3, 4… peb tuaj yeem muab cov npe no ua singlets, doublets, triplets, quartets, thiab lwm yam.
Ntau yam yog ntsuas txheeb ze rau orbital angular momentum. Qhov ntawd txhais tau tias; nws yog ntsuas txheeb ze rau tus naj npawb ntawm ze li ntawm degenerate zog theem, uas txawv ntawm ib leeg raws li lub spin-orbit sib cuam tshuam lub zog. Piv txwv li, cov organic tebchaw ruaj khov muaj cov khoom siv hluav taws xob ua tiav uas tsis muaj cov hluav taws xob tsis sib xws. Yog li ntawd, cov molecules muaj singlet, hauv av xeev.
Daim ntawv cog lus yog dab tsi?
Daim ntawv cog lus yog hais txog kev ntsuas ntawm tus lej ntawm cov hluav taws xob hauv cov ntawv cog lus tshuaj. Lub tswvyim ntawm daim ntawv cog lus tau tsim los ntawm Linus Pauling. Nws yog ib qho tseem ceeb raws li qhov taw qhia ntawm kev ruaj ntseg ntawm ib daim ntawv cog lus tshuaj. Siab dua tus nqi ntawm daim ntawv cog lus, muaj zog cov tshuaj lom neeg daim ntawv cog lus. Yog tias tsis muaj cov tshuaj tiv thaiv kab mob sib kis, cov ntawv cog lus sib npaug ntawm cov ntawv cog lus ntawm ob lub atom ntawm ib lub molecule. Qhov no yog vim qhov kev txiav txim ntawm daim ntawv cog lus yog sib npaug ntawm cov khoom siv hluav taws xob sib faib los ntawm ob (cov khoom siv tshuaj muaj ob lub electrons ib daim ntawv cog lus). Qhov sib npaug rau kev suav ntawm daim ntawv cog lus hauv ib qho molecule yog raws li hauv qab no:
Daim ntawv cog lus=(tus lej ntawm cov khoom siv hluav taws xob - tus lej ntawm cov khoom siv hluav taws xob tiv thaiv) / 2
Raws li qhov sib npaug saum toj no, yog tias daim ntawv cog lus txiav txim siab xoom, ob lub atoms tsis sib koom ua ke. Piv txwv li, daim ntawv cog lus rau dinitrogen molecule yog 3. Ntxiv mus, cov hom isoelectronic feem ntau muaj tib daim ntawv cog lus. Tsis tas li ntawd, lub tswv yim ntawm daim ntawv cog lus muaj txiaj ntsig zoo hauv molecular dynamics thiab daim ntawv cog lus muaj peev xwm.
Dab tsi yog qhov txawv ntawm Kev Sib Tw thiab Daim Ntawv Cog Lus?
Lub tswv yim ntawm ntau qhov sib txawv yog qhov tseem ceeb hauv quantum chemistry, thaum lub tswv yim ntawm daim ntawv cog lus yog qhov tseem ceeb hauv molecular dynamics. Qhov sib txawv tseem ceeb ntawm kev sib npaug thiab daim ntawv cog lus yog qhov sib txawv yog hais txog tus naj npawb ntawm qhov ua tau taw qhia ntawm lub zog ntawm qib, qhov kev txiav txim siab yog hais txog kev ntsuas ntawm cov hluav taws xob hauv cov khoom siv tshuaj lom neeg.
Qhov sib npaug rau kev txiav txim siab ntawm ntau qhov ntau yog 2S + 1 qhov twg S yog tag nrho cov kiv puag ncig lub zog. Qhov sib npaug rau kev txiav txim siab ntawm daim ntawv cog lus yog (bonding electrons + antibonding electrons) / 2. Ntxiv mus, qhov sib npaug yog ntsuas raws li tus nqi txheeb ze (uas yog txheeb ze rau lub orbital angular momentum). Tab sis, daim ntawv cog lus daim ntawv cog lus yog ib qho txiaj ntsig tshwj xeeb rau ib daim ntawv cog lus tshuaj. Feem ntau, yog tias daim ntawv cog lus yog xoom, nws txhais tau tias tsis muaj tshuaj lom neeg daim ntawv cog lus.
Hauv qab infographic qhia txog qhov sib txawv ntawm ntau qhov sib txawv thiab daim ntawv cog lus.
Summary – Multiplicity vs Bond Order
Lub tswv yim ntawm ntau qhov sib txawv yog qhov tseem ceeb hauv quantum chemistry, thaum lub tswv yim ntawm daim ntawv cog lus yog qhov tseem ceeb hauv molecular dynamics. Qhov sib txawv tseem ceeb ntawm kev sib npaug thiab daim ntawv cog lus yog qhov sib txawv yog hais txog tus naj npawb ntawm qhov ua tau taw qhia ntawm qhov tig ntawm lub zog theem thaum daim ntawv cog lus hais txog kev ntsuas ntawm tus lej ntawm cov hluav taws xob hauv cov khoom siv tshuaj lom neeg.
