transition states - 2026 ACF Regionals

Question

These entities can be found by generating equidistant, spring-connected “images” in a modification to the nudged elastic band or NEB method. For 10 points each:

[10m] Name these entities that correspond to local maxima on a reaction coordinate diagram. “Late” types of these entities resemble products according to Hammond’s postulate.

ANSWER: transition states [accept TS; prompt on activated complexes]

[10e] Transition states can be identified by finding paths that minimize this quantity on their namesake surfaces. The Hamiltonian of a given system is composed of terms for this quantity and its kinetic counterpart.

ANSWER: potential energy [accept potential energy surfaces or PES; prompt on energy]

[10h] Unlike NEB, this method uses molecular geometry constraints to interpolate linear or quadratic paths through a maxima. Peng and Schlegel applied quasi-Newton methods to optimize results first obtained using this method.

ANSWER: synchronous transit methods [accept linear synchronous transit methods or LSTs; accept quadratic synchronous transit methods or QSTs; accept synchronous transit-guided quasi-Newton methods or STQNs; prompt on transit methods]

<Purdue, Chemistry>

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Summary


California (North)	Main Site	Y	3	16.67	100%	67%	0%
California (South)	Main Site	Y	3	20.00	100%	100%	0%
Canada	Main Site	Y	9	15.56	89%	56%	11%
Florida	Main Site	Y	3	10.00	100%	0%	0%
Great Lakes	Main Site	Y	5	18.00	100%	80%	0%
Lower Mid-Atlantic	Main Site	Y	5	14.00	80%	60%	0%
Midwest	Main Site	Y	8	17.50	100%	63%	13%
Overflow	Main Site	Y	4	15.00	100%	50%	0%
South Central	Main Site	Y	2	15.00	100%	50%	0%
Southeast	Main Site	Y	6	18.33	100%	83%	0%
UK	Main Site	Y	9	18.89	100%	89%	0%
Upper Mid-Atlantic	Main Site	Y	6	18.33	100%	83%	0%
Upstate NY	Main Site	Y	4	17.50	75%	75%	25%

Data


Berkeley D	Berkeley B	0	10	0	10
Stanford A	Berkeley A	10	10	0	20
Berkeley C	Stanford B	10	10	0	20
UCSD B	UC Irvine	10	10	0	20
UCSD A	UCLA A	10	10	0	20
Brock	Toronto G	0	0	0	0
UCSD C	UCLA B	10	10	0	20
McGill B	Toronto C	0	10	0	10
McGill A	Toronto E	0	10	0	10
UBC A	Ottawa	10	10	0	20
UBC B	Waterloo B	10	10	0	20
Waterloo A	Queen's	10	10	10	30
Western C	Simon Fraser	0	10	0	10
Central Florida A	Florida B	0	10	0	10
Florida A	Central Florida B	0	10	0	10
Central Florida C	Florida C	0	10	0	10
CWRU B	Michigan C	10	10	0	20
Michigan A	CWRU A	10	10	0	20
Pittsburgh	Michigan B	10	10	0	20
Ohio State B	Ohio State A	10	10	0	20
Michigan State	Ohio State C	0	10	0	10
Carleton University	Guelph	10	10	0	20
Toronto B	McMaster A	10	10	0	20
Duke	South Carolina B	0	10	0	10
Liberty A	NC State B	0	0	0	0
North Carolina A	NC State A	10	10	0	20
Virginia Tech A	William and Mary	10	10	0	20
Virginia Tech B	Wake Forest	10	10	0	20
Northwestern C	Chicago A	0	10	0	10
Chicago C	Indiana B	10	10	0	20
Illinois C	Chicago D	10	10	0	20
Indiana A	Chicago E	10	10	0	20
Illinois A	Indiana C	10	10	10	30
Illinois B	Northwestern D	10	10	0	20
Purdue B	Notre Dame A	0	10	0	10
Chicago B	Notre Dame B	0	10	0	10
Georgia Tech A	Carleton College	10	10	0	20
Missouri B	Claremont	0	10	0	10
Iowa State	Missouri A	0	10	0	10
Minnesota A	Washington B	10	10	0	20
Texas A&M A	Texas A	0	10	0	10
Texas B	Murray State A	10	10	0	20
Alabama B	Kentucky	0	10	0	10
Georgia Tech B	Tennessee B	10	10	0	20
Bruin	Louisville A	10	10	0	20
Georgia Tech C	Sewanee	10	10	0	20
WashU A	Louisville B	10	10	0	20
Georgia Tech D	WashU B	10	10	0	20
Cambridge C	Bristol	10	10	0	20
Edinburgh A	Southampton A	10	10	0	20
Imperial A	City St. George's	10	10	0	20
LSE	Imperial C	0	10	0	10
Manchester	Imperial B	10	10	0	20
Cambridge A	Montpellier	10	10	0	20
Oxford A	Edinburgh B	10	10	0	20
Cambridge B	Oxford B	10	10	0	20
Warwick A	Oxford C	10	10	0	20
Swarthmore	John Jay	10	10	0	20
Columbia B	Maryland A	10	10	0	20
Georgetown	NYU A	0	10	0	10
NYU B	Johns Hopkins B	10	10	0	20
Rutgers A	NYU C	10	10	0	20
Cornell A	Binghamton A	10	0	10	20
RIT	Binghamton B	10	10	0	20
Penn State	Cornell B	10	10	0	20
Rochester	Cornell C	0	10	0	10
Johns Hopkins A	Columbia C	10	10	0	20