{"id":6233,"date":"2026-10-19T09:48:39","date_gmt":"2026-10-19T09:48:39","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-efnafraedi-vilhjalmur-asgeirsson\/"},"modified":"2026-10-19T09:48:39","modified_gmt":"2026-10-19T09:48:39","slug":"doktorsvorn-i-efnafraedi-vilhjalmur-asgeirsson","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-efnafraedi-vilhjalmur-asgeirsson\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed efnafr\u00e6\u00f0i – Vilhj\u00e1lmur \u00c1sgeirsson"},"content":{"rendered":"
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Streymi:\u00a0https:\/\/livestream.com\/hi\/doktorsvornvilhjalmurasgeirsson<\/a> <\/strong><\/p>\n

Doktorsefni:<\/strong>\u00a0Vilhj\u00e1lmur \u00c1sgeirsson<\/p>\n

Heiti ritger\u00f0ar:<\/strong>\u00a0\u00der\u00f3un og mat \u00e1 a\u00f0fer\u00f0um fyrir t\u00f6lvureikninga \u00e1 efnahv\u00f6rfum (Development and evaluation of computational methods for studies of chemical reactions)<\/p>\n

Andm\u00e6lendur
<\/strong>Dr. G\u00edsli H\u00f3lmar J\u00f3hannesson, kennari vi\u00f0 Keili \u2013 H\u00e1sk\u00f3labr\u00fa.
Dr. Baron Peters, pr\u00f3fessor vi\u00f0 H\u00e1sk\u00f3lann \u00ed Illinois Urbana – Champaign<\/p>\n

Lei\u00f0beinandi:<\/strong>\u00a0Dr. Hannes J\u00f3nsson, pr\u00f3fessor vi\u00f0 Raunv\u00edsindadeild H\u00e1sk\u00f3la \u00cdslands<\/p>\n

Einnig \u00ed doktorsnefnd:<\/strong>
<\/strong>Dr. Egill Sk\u00falason, pr\u00f3fessor vi\u00f0 I\u00f0na\u00f0arverkfr\u00e6\u00f0i-, v\u00e9laverkfr\u00e6\u00f0i- og t\u00f6lvunarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands
Dr. Elvar \u00d6rn J\u00f3nsson, s\u00e9rfr\u00e6\u00f0ingur \u00e1 Raunv\u00edsindastofnun H\u00e1sk\u00f3lans.<\/p>\n

Doktorsv\u00f6rn st\u00fdrir:<\/strong>\u00a0Dr. Einar \u00d6rn Sveinbj\u00f6rnsson, pr\u00f3fessor og deildarforseti Raunv\u00edsindadeildar H\u00e1sk\u00f3la \u00cdslands<\/p>\n

\u00c1grip<\/strong><\/p>\n

A\u00f0fer\u00f0ir til \u00feess a\u00f0 finna hvarfgang og meta hra\u00f0a efnahvarfa eru \u00fer\u00f3a\u00f0ar og pr\u00f3fa\u00f0ar \u00e1 fj\u00f6lbreytilegum kerfum, \u00fear sem b\u00e6\u00f0i klass\u00edsk og skammtafr\u00e6\u00f0ileg l\u00fdsing \u00e1 at\u00f3mkj\u00f6rnum er notu\u00f0. Fyrir klass\u00edska l\u00fdsingu \u00e1 at\u00f3munum eru fundnir l\u00e1gmarksorkuferlar sem tengja tv\u00f6 orkul\u00e1gm\u00f6rk og samsvara st\u00f6\u00f0ugum \u00e1st\u00f6ndum kerfisins. \u00c1 sl\u00edkum ferli samsvarar orkuh\u00e1mark fyrsta stigs s\u00f6\u00f0ulpunkti \u00e1 orkuyfirbor\u00f0inu og gefur mat \u00e1 virkjunarorkunni fyrir hvarfi\u00f0. En fyrir skammtafr\u00e6\u00f0ilega l\u00fdsingu \u00e1 at\u00f3munum er besti smugferillinn fundinn. \u00deessi ferill samsvarar fyrsta stigs s\u00f6\u00f0ulpunkti \u00e1 verkunaryfirbor\u00f0inu og er oft kenndur vi\u00f0 snareindir. \u00dat fr\u00e1 sl\u00edkum punkti er h\u00e6gt a\u00f0 reikna hra\u00f0a \u00e1 varma\u00f6rvu\u00f0u smugi. Til \u00feess a\u00f0 h\u00e6gt s\u00e9 a\u00f0 kanna sl\u00edk yfirbor\u00f0 og finna \u00feessa ferla \u00fearf a\u00f0 reikna orku og kraftinn sem verkar \u00e1 at\u00f3min. Sl\u00edkir reikningar fela yfirleitt \u00ed s\u00e9r \u00feunga t\u00f6lvu\u00fatreikninga. \u00dev\u00ed er afar mikilv\u00e6gt a\u00f0 \u00fer\u00f3a a\u00f0fer\u00f0ir sem eru b\u00e6\u00f0i n\u00e1kv\u00e6mar og hagkv\u00e6mar a\u00f0 \u00fev\u00ed leyti a\u00f0 sem f\u00e6sta orku og kraftareikninga \u00feurfi til.<\/p>\n

Hinar \u00fdmsu afer\u00f0ir sem eru \u00fer\u00f3a\u00f0ar h\u00e9r eru \u00fatv\u00edkkanir \u00e1 hinni vel \u00feekktu teygjubandsa\u00f0fer\u00f0, NEB. \u00cd \u00feessari a\u00f0fer\u00f0 er ferill, sem er l\u00fdst sem safni af hnitum at\u00f3manna, f\u00e6r\u00f0ur \u00ed \u00e1tt a\u00f0 lausnarferlinum, anna\u00f0hvort l\u00e1gmarksorkuferli e\u00f0a besta smugferli, me\u00f0 \u00edtrun. Hver punktur \u00ed \u00feessari strj\u00e1lu l\u00fdsingu \u00e1 ferlinum er \u00fe\u00e1 f\u00e6r\u00f0ur ni\u00f0ur eftir yfirbor\u00f0inu \u00ed stefnu hornr\u00e9tt \u00e1 ferilinn og gormkraftar nota\u00f0ir til \u00feess a\u00f0 vi\u00f0halda jafndreifingu \u00e1 punktunum eftir ferlinum. \u00deetta krefst \u00feess a\u00f0 hafa n\u00f3gu gott mat \u00e1 snertlinum eftir ferlinum til \u00feess a\u00f0 framkv\u00e6ma v\u00f6rpun \u00e1 kr\u00f6ftunum \u00ed hornr\u00e9tta og sams\u00ed\u00f0a \u00fe\u00e6tti. \u00cd fyrsta hluta verksins er hagkv\u00e6mni teygjubandsa\u00f0fer\u00f0arinnar fyrir reikninga \u00e1 l\u00e1gmarksorkuferlum fyrir sameindahv\u00f6rf metin og betrumb\u00e6tt. Raunin er a\u00f0 oft er \u00fe\u00f6rf \u00e1 a\u00f0 nota \u00f3\u00fearflega mikla reiknigetu fyrir teygjubandsreikninga \u00e1 sl\u00edkum hv\u00f6rfum, \u00fear sem orkan \u00e1 l\u00e1gmarksorkuferlinum breytist oft l\u00edti\u00f0 sem ekkert \u00e1 k\u00f6flum. \u00dear af lei\u00f0andi er reikniafli s\u00f3a\u00f0 \u00ed a\u00f0 l\u00fdsa l\u00edtilv\u00e6gum hluta ferilsins \u00e1 sama t\u00edma og upplausn ferilsins er ekki n\u00e6gjanlega g\u00f3\u00f0 til a\u00f0 f\u00e1 mat \u00e1 snertilnum \u00e1 mikilv\u00e6gum hluta hans. \u00deetta getur haft mikil \u00e1hrif \u00e1 kostna\u00f0 teygjubandsreikninga og getur jafnvel orsaka\u00f0 \u00fea\u00f0 a\u00f0 samleitni n\u00e1ist ekki. Tv\u00e6r breytingar \u00e1 teygjubandsa\u00f0fer\u00f0inni eru settar fram \u00fear sem \u00e1hersla er l\u00f6g\u00f0 \u00e1 mikilv\u00e6gasta hluta l\u00e1gmarksorkuferilsins, \u00fe.e. \u00feann hluta sem inniheldur h\u00e6sta orkuh\u00e1marki\u00f0. \u00cd annarri a\u00f0fer\u00f0inni er veikri samleitni \u00e1 l\u00e1gmarksorkuferlinum fyrst n\u00e1\u00f0 og s\u00ed\u00f0an er n\u00fdju punktasafni sj\u00e1lfvirkt dreift \u00e1 sv\u00e6\u00f0i orkuh\u00f3lsins til \u00feess a\u00f0 b\u00e6ta upplausnina \u00e1 ferlinum \u00ed grennd vi\u00f0 h\u00e1marki\u00f0. \u00cd hinni a\u00f0fer\u00f0inni er auknum \u00fe\u00e9ttleika punkta n\u00e1\u00f0 \u00e1 \u00feessu mikilv\u00e6ga sv\u00e6\u00f0i l\u00e1gmarksorkuferilsins me\u00f0 sk\u00f6lun \u00e1 styrkleika gormkraftsins samkv\u00e6mt orkugildi punktanna, \u00fear sem gormarnir eru ger\u00f0ir st\u00edfari \u00e1 h\u00e1orkusv\u00e6\u00f0um \u00e1 me\u00f0an \u00edtranirnar eru framkv\u00e6mdar. Reynslan mun s\u00fdna hvor a\u00f0fer\u00f0in, e\u00f0a m\u00f6gulega samsetning beggja, er hagkv\u00e6mari. Me\u00f0 \u00fev\u00ed a\u00f0 setja saman teygjubandsa\u00f0fer\u00f0ina og eiginvigra-rakningu er dregi\u00f0 enn frekar \u00far reiknikostna\u00f0i \u00feegar leita\u00f0 er a\u00f0 s\u00f6\u00f0ulpunktum. \u00cd \u00feeirri a\u00f0fer\u00f0 er gr\u00f3fri samleitni \u00e1 l\u00e1gmarksorkuferlinum n\u00e1\u00f0. Uppl\u00fdsingum er s\u00ed\u00f0an safna\u00f0 af ferlinum, \u00fe.m.t punktinum me\u00f0 h\u00e6stu orkuna. \u00deessar uppl\u00fdsingar eru sj\u00e1lfvirkt nota\u00f0ar til \u00feess a\u00f0 byrja eiginvigra-rakningu sem au\u00f0veldlega n\u00e6r samleitni \u00e1 s\u00f6\u00f0ulpunktinn sem svarar til vi\u00f0komandi efnahvarfs. A\u00f0fer\u00f0irnar eru nota\u00f0ar \u00e1 \u00fdmis efnahv\u00f6rf og \u00e1 gagnasafn sem inniheldur 121 sameindahv\u00f6rf. A\u00f0fer\u00f0irnar hafa veri\u00f0 innleiddar \u00ed ORCA skammtaefnafr\u00e6\u00f0i hugb\u00fana\u00f0inn sem n\u00fdtur \u00f6rt vaxandi vins\u00e6lda og er \u00e1 g\u00f3\u00f0ri lei\u00f0 me\u00f0 a\u00f0 ver\u00f0a \u00fatbreiddasti hugb\u00fana\u00f0ur \u00ed heimi fyrir rafeindastr\u00fakt\u00farreikninga \u00ed efnafr\u00e6\u00f0i.<\/p>\n

\u00cd \u00f6\u00f0rum hluta verksins er l\u00f6g\u00f0 \u00e1hersla \u00e1 skammtafr\u00e6\u00f0ilega l\u00fdsingu at\u00f3manna og leit a\u00f0 bestu smugferlum. Besti smugferill fylgir s\u00f6mu lei\u00f0 og snareind \u00e1 verkunaryfirbor\u00f0inu og \u00fev\u00ed er h\u00e6gt a\u00f0 nota besta smugferilinn til \u00feess a\u00f0 reikna \u00fat skammtafr\u00e6\u00f0ilegan smughra\u00f0a efnahvarfa. Reikningar \u00e1 bestu smugferlum eru hagkv\u00e6mari en hef\u00f0bundna leitara\u00f0fer\u00f0in sem notu\u00f0 hefur veri\u00f0 til \u00feess a\u00f0 finna snareindir. A\u00f0al\u00e1st\u00e6\u00f0an fyrir \u00feessari auknu hagkv\u00e6mi er s\u00fa a\u00f0 h\u00e6gt er a\u00f0 stj\u00f3rna dreifingu punktanna \u00e1 ferlinum \u00ed leitinni a\u00f0 besta smugferlinum, \u00e1 me\u00f0an flestir punktarnir enda \u00ed grennd vi\u00f0 endapunktana \u00ed snareindareikningum. \u00dev\u00ed er h\u00e6gt a\u00f0 nota f\u00e6rri punkta til a\u00f0 n\u00e1 g\u00f3\u00f0ri upplausn \u00e1 ferlinum \u00ed reikningum \u00e1 bestu smugferlum \u00ed samanbur\u00f0i vi\u00f0 snareindareikninga.<\/p>\n

\u00cd fyrstu tveimur hlutum verksins er notast vi\u00f0 \u00fe\u00e9ttnifellafr\u00e6\u00f0i til a\u00f0 reikna rafeindastr\u00fakturinn eins og almennt t\u00ed\u00f0kast n\u00fa \u00ed reikniefnafr\u00e6\u00f0i. Aftur \u00e1 m\u00f3ti getur val \u00e1 vi\u00f0eigandi orkuyfirbor\u00f0i fyrir reikninga \u00e1 sameindum og efnahv\u00f6rfum oft reynst erfitt. Me\u00f0 \u00feetta \u00ed huga er s\u00e9rstaklega \u00e1hugaver\u00f0 og erfi\u00f0 d\u00edam\u00edn-katj\u00f3n sko\u00f0u\u00f0 \u00ed \u00feri\u00f0ja hluta verksins. Tilraunam\u00e6lingar \u00e1 \u00feessari sameind hafa veri\u00f0 t\u00falka\u00f0ar \u00feannig a\u00f0 b\u00e6\u00f0i s\u00e9 h\u00e6gt a\u00f0 finna sta\u00f0bundi\u00f0 og \u00f3sta\u00f0bundi\u00f0 rafeinda\u00e1stand. Hef\u00f0bundnar rafeindastr\u00fakt\u00fara\u00f0fer\u00f0ir s\u00fdna hins vegar ekki tilvist sta\u00f0bundna rafeinda\u00e1standsins, til d\u00e6mis vins\u00e6l rafeinda\u00fe\u00e9ttleikafelli og jafnvel coupled-cluster (singles-doubles-(triples)) a\u00f0fer\u00f0in. N\u00e1kv\u00e6mir og fl\u00f3knir fj\u00f6l\u00e1stands-bylgjufallsreikningar (e. multireference wavefunction calculations) eru nota\u00f0ir til a\u00f0 varpa lj\u00f3si \u00e1 \u00feetta misr\u00e6mi \u00e1 milli rafeindareikninga og tilrauna og skera \u00far um tilvist sta\u00f0bundna rafeinda\u00e1standsins. \u00cd samr\u00e6mi vi\u00f0 ni\u00f0urst\u00f6\u00f0ur tilraunar sp\u00e1 \u00feessir n\u00e1kv\u00e6mari reikningar fyrir um tilvist sta\u00f0bundna \u00e1standsins.<\/p>\n

Um doktorsefni\u00f0<\/strong><\/p>\n

Vilhj\u00e1lmur \u00c1sgeirsson er f\u00e6ddur \u00e1ri\u00f0 1988. Hann lauk BS-gr\u00e1\u00f0u \u00ed efnafr\u00e6\u00f0i fr\u00e1 H\u00e1sk\u00f3la \u00cdslands \u00e1ri\u00f0 2013 og meistaragr\u00e1\u00f0u \u00ed efnafr\u00e6\u00f0i fr\u00e1 sama sk\u00f3la \u00e1ri\u00f0 2015. A\u00f0 loknu meistaran\u00e1mi vann hann sem a\u00f0sto\u00f0arranns\u00f3knarma\u00f0ur vi\u00f0 H\u00e1sk\u00f3lann \u00ed Bonn fr\u00e1 2016-2017. Vilhj\u00e1lmur h\u00f3f doktorsn\u00e1m vi\u00f0 H\u00e1sk\u00f3la \u00cdslands \u00e1ri\u00f0 2017.<\/p>\n<\/div><\/div>","protected":false},"featured_media":5000,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2021-06-24T14:00:00+00:00","_phd_date_end":"2021-06-24T16:00:00+00:00","_phd_location":"Askja Stofa 132","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"\u00der\u00f3un og mat \u00e1 a\u00f0fer\u00f0um fyrir t\u00f6lvureikninga \u00e1 efnahv\u00f6rfum (Development and evaluation of computational methods for studies of chemical reactions)","_phd_source_url":"https:\/\/gamli.hi.is\/vidburdir\/doktorsvorn_i_efnafraedi_vilhjalmur_asgeirsson","_phd_source_node_id":"375699","_phd_source_type":"vidburdir","_phd_member_id":759,"footnotes":""},"phd_school":[101,93],"phd_discipline":[102],"class_list":["post-6233","phd_defence","type-phd_defence","status-publish","has-post-thumbnail","hentry","phd_school-raunvisindadeild","phd_school-verkfraedi-og-natturuvisindasvid","phd_discipline-phd-i-efnafraedi"],"_links":{"self":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence\/6233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence"}],"about":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/types\/phd_defence"}],"version-history":[{"count":0,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_defence\/6233\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/media\/5000"}],"wp:attachment":[{"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/media?parent=6233"}],"wp:term":[{"taxonomy":"phd_school","embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_school?post=6233"},{"taxonomy":"phd_discipline","embeddable":true,"href":"https:\/\/phd.hi.is\/en\/wp-json\/wp\/v2\/phd_discipline?post=6233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}