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Title: Active Thermochemical Tables: Thermochemistry for the 21st Century


1
Active Thermochemical Tables Thermochemistry
for the 21st Century
Branko Ruscic, R. E Pinzon, G. von Laszewski,
D. Kodeboyina, A. Burcat (Technion), D. Leahy
(SNL), D. Montoya (LANL), and A. F. Wagner
Argonne National Laboratory, Argonne, IL
A U.S. Department of Energy Office of Science
Laboratory Operated by The University of Chicago
Office of Science
U.S. DEPARTMENT OF ENERGY
2
THANKS TO…
  • Supported by the U.S. Department of Energy

Division of Chemical Sciences, Geosciences and
Biosciences, Office of Basic Energy Sciences,

and Division of Mathematical, Information and
Computational Sciences, Office of Advanced
Scientific Computing Research
  • Numerous collaborators
  • CMCS Team
  • IUPAC Task Group for Thermochemistry of Radicals
  • Melita L. Morton (ANL/postddoc), Sandra J.
    Bittner (ANL), Sandeep G. Nijsure (ANL), Michael
    Minkoff (ANL), Lawrence B. Harding (ANL), Joe V.
    Michael (ANL), Stephen Gray (ANL), John Stanton
    (UT Austin), Attila Csaszar (ELTE Budapest),
    Mihaly Kallay (U. Mainz), Tamas Turanyi (ELTE
    Budapest), David A. Dixon (U. Ala.), David
    Feller (PNNL), Kirk Peterson (PNNL/WSU), David
    Schwenke (NASA Ames), Cheuk-Yiu Ng (UC Davis)…

3
WHAT ARE ACTIVE THERMOCHEMICAL TABLES?
4
WHAT ARE ACTIVE THERMOCHEMICAL TABLES?
  • Active Thermochemical Tables (ATcT) a novel
    scientific application, centered on a
    distinctively different paradigm of how to
    derive accurate, reliable, and internally
    consistent thermochemical values
  • thermochemistry as it befits the 21st century
  • rapidly becoming the archetypal approach (ATcT
    are appearing as a new encyclopedic term in the
    2005 Yearbook of Science and Technology, an
    annual update to the McGraw-Hill Encyclopedia of
    Science and Technology)
  • first implementation of the broader idea of
    Active Tables

5
WHAT IS THE GENERAL IDEA BEHIND ACTIVE TABLES?
  • Many databases store and display data items that
  • are not directly measurable observables, and
  • are interdependent in a non-transparent way,
  • because they are
  • derived in a (usually) complex way from more
    basic determinations
  • In most cases, these databases do not expose or
    even store either
  • the basic determinations, or
  • the data interdependencies
  • Dear consequence
  • the database cannot be easily updated when new
    information becomes available and hence becomes
    obsolete
  • The idea behind Active Tables is not to store
    derived data, but rather the basic determinations
    and the dependencies, and update the derived data
    as frequently as needed

6
WHAT DO WE NEED GOOD THERMOCHEMISTRY FOR?
  • Knowledge of thermochemical stability of chemical
    species is central to chemistry and essential in
    many industries
  • Accurate, reliable, and self-consistent
    thermochemistry is
  • a conditio sine qua non in chemical kinetics,
    construction of reaction mechanisms, formulation
    of multi-scale chemical models that have
    predictive abilities, etc.
  • historically the strongest spiritus movens for
    the development and improvement of electronic
    structure theories
  • a stimulating environment fostering abstraction
    of generalities leading to new insights into
    details of chemical bonding
  • Availability of well-defined and properly
    quantified uncertainties is becoming increasingly
    important as the fidelity levels of electronic
    structure theory and computer modeling of complex
    chemical environments are increasing

7
THERMOCHEMICAL TABLES
  • Tabulations of thermochemical properties,
    conveniently sorted by chemical species
  • Tabulated thermochemical properties are derived
    from other, more direct determinations
  • Species-interrelating determinations (D0,
    DrHT, KeqT, electrode potentials, solub.
    consts, etc) ? DfH and/or DfG at one
    temperature
  • Species-specific determinations (lists of
    levels, spectroscopic constants, direct
    measurements of Cp , etc) ? partition-function
    QT related thermochemical info HT-H0/RT
    T ?(ln QT)/?T ltEgt/kT ò CpT/R dT ST/R
    T ?(ln QT)/?T ln QT ltEgt/kT ln QT ò
    CpT/R/T dT FT/R ln QT ST/R -
    HT-H0/RT CpT/R T2 ?2(ln QT)/?T2 2 T
    ?(ln QT)/?T ltE2gt/(kT)2 - (ltEgt/kT)2 and
    T-dependence of DfH and DfG

8
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9
TRADITIONAL SEQUENTIAL THERMOCHEMISTRY
  • The nature of the inexorable species-interrelatin
    g determinations causes considerable
    complications…
  • Traditional approach sequential thermochemistry
  • one target species per step
  • available species-interrelating information
    relating the target species to those previously
    determined is examined
  • the best determination is selected manually and
    used to derive DfH at one T
  • available species-specific info is used to derive
    T-dependence and other functions
  • thermochemistry for the target species is frozen
    and used as a constant in subsequent steps
  • sequence follows the standard order of the
    elements

10
DEFICIENCIES OF THE TRADITIONAL APPROACH
  • Traditional thermochemical tables have a maze of
    hidden progenitor-progeny relationships
  • Consequently, traditional tables are next to
    impossible to properly update with new knowledge
  • New determinations can be used, at best, to
    improve things locally, for one target species
  • This immediately introduces new inconsistencies
    across the table, since there will be other
    species pegged to the old value of the newly
    revised species it is not explicit which those
    may be
  • The adopt and freeze sequential approach
  • creates a hidden cumulative error (lack of
    feedback to frozen values)
  • produces uncertainties that do not properly
    reflect all the knowledge that was available
    (e.g. knowledge used only during later steps, or
    was discarded because it lagged behind the
    selected best determination) (BTW,
    uncertainties are the NBT)
  • Available knowledge is used only partially, at
    best

11
THE APPROACH OF ACTIVE THERMOCHEMICAL TABLES
  • As opposed to conventional sequential
    thermochemistry, Active Thermochemical Tables
    are based on the Thermochemical Network
    approach, hence
  • addressing and correcting the mentioned
    deficiencies of traditional tables, and, at the
    same time
  • introducing a number of completely new features
    (such as rapid update with new information,
    what if tests, weakest link isolation,
    availability of the full covariance matrix,
    the sensitivity matrix, etc.)

12
WHAT IS A THERMOCHEMICAL NETWORK ?
CH
13
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CH
C
14
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CH
C
15
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CH
C
16
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CH
C
17
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
18
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
C(grph) CO2 2CO
19
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
C(grph) CO2 2CO
CO H2O CO2 H2
20
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
C(grph) CO2 2CO
C(grph) O2 CO2
CO H2O CO2 H2
21
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
C(grph) CO2 2CO
C(grph) O2 CO2
CO H2O CO2 H2
DvapH(H2O)
22
WHAT IS A THERMOCHEMICAL NETWORK ?
H
CO 1/2O2 CO2
CH
C
C(grph) CO2 2CO
C(grph) O2 CO2
CO H2O CO2 H2
DvapH(H2O)
H2 1/2O2 H2O(l)
23
WHAT IS A THERMOCHEMICAL NETWORK ?
24
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Primary vertices sought-for enthalpies of
    formation

25
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Secondary vertices experimentally/theoretically
    accessible quantities (DHr, DGr, Keq,…)

26
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Edges (directed and weighted) participation in
    chemical reactions

27
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Secondary vertices may have multiple
    degeneracies (competing measurements)

28
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

29
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

30
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

31
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

32
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

33
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

34
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices

35
WHAT IS A THERMOCHEMICAL NETWORK ?
  • Generally there will be a significant number of
    alternative paths between primary vertices
  • The best set of ?Hfs describing all underlying
    knowledge is obtained NOT by choosing a
    particular sequential path through the TN,

but by simultaneous solution of the network (via
minimization of a suitable statistic, such as
c2), preceded by a statistical analysis of TN
(to isolate optimistic uncertainties)
36
SOLVING THE THERMOCHEMICAL NETWORK
  • TN preconditioning is very important
    optimistic uncertainties will skew the result

37
SOLVING THE THERMOCHEMICAL NETWORK
  • TN preconditioning ? redundant loops check

38
SOLVING THE THERMOCHEMICAL NETWORK
  • TN preconditioning ? worst offender
    strategy ( intelligent Occams razor)

39
SOLVING THE THERMOCHEMICAL NETWORK
  • TN preconditioning ? Bayesian logic, Nash
    games,…

40
SOME ADVANTAGES OF ACTIVE THERMOCHEMICAL TABLES
  • The solutions (?fHs) are superior to
    conventional tables
  • values are globally consistent with all input
    data
  • uncertainties properly reflect all relationships
    presented as input
  • Allows painless propagation of new data with all
    its consequences
  • Opens a new venue of rapid availability of latest
    information (including tentative data, if so
    desired)
  • Allows what if tests of
  • new data for consistency (or lack thereof) with
    existing knowledge
  • educational explorations, including hypothetical
    data
  • By finding the weakest links in the Network it
    can suggest new experiments/calculations that
    will have the highest impact on current knowledge
    (by itself a new paradigm)
  • Supporting documents relating to input data (raw
    data, notes, pdfs of papers, other pedigree
    information) are easily incorporated for
    examination

41
Collaboratory for Multi-scale Chemical Science
(CMCS)
  • CMCS is one of the SciDAC National
    Collaboratories
  • Brings together scientists from various fields to
    develop an open knowledge grid and the associated
    community portal for multi-scale chemistry
    research
  • Uses advanced collaboration, data management and
    annotation technologies
  • The goal is to conquer current barriers to rapid
    sharing of validated information

42
Collaboratory for Multi-scale Chemical Science
(CMCS)
  • CMCS is one of the SciDAC National
    Collaboratories
  • Brings together scientists from various fields to
    develop an open knowledge grid and the associated
    community portal for multi-scale chemistry
    research
  • Uses advanced collaboration, data management and
    annotation technologies
  • The goal is to conquer current barriers to rapid
    sharing of validated information

43
ACTIVE THERMOCHEMICAL TABLES
CMCS
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal
  • via an integrated portlet

44
ACTIVE THERMOCHEMICAL TABLES
CMCS
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal
  • via an integrated portlet

45
ACTIVE THERMOCHEMICAL TABLES
CMCS
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet

CH3
46
ACTIVE THERMOCHEMICAL TABLES
CMCS
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet

1CH2 H2O CH3 OH
47
ACTIVE THERMOCHEMICAL TABLES
CMCS
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet

Reaction network
48
ACTIVE THERMOCHEMICAL TABLES
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet

49
ACTIVE THERMOCHEMICAL TABLES
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet
  • The ATcT back-end system consists of a kernel

50
ACTIVE THERMOCHEMICAL TABLES
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet
  • The ATcT back-end system consists of a kernel
  • and the underlying collection of
    thermochemically relevant data

51
ACTIVE THERMOCHEMICAL TABLES
  • The current stable version of ATcT is running as
    a web service
  • Accessible from the CMCS portal via an integrated
    portlet
  • The ATcT back-end system consists of a kernel
  • and the underlying collection of
    thermochemically relevant data
  • The ATcT kernel is quite complex it is
    internally modular (eases program maintenance)
    and has so far 60,000 lines of Fortran 95 code
    (modifiable to HPF, which runs on parallel
    clusters, needed for handling large networks)

52
ATcT DATA ORGANIZATION
  • The underlying data is organized in a number of
    Libraries and Notes
  • Libraries are large collections of data,
    typically generated by committees who oversee and
    anoint their scientific soundness
  • Notes are lighter versions of Libraries,
    typically associated with individual users or
    collaborative workgroups
  • Main Library contains the Core (Argonne)
    Thermochemical Network
  • Auxiliary Libraries contain data that reproduce
    information in historical static tables for
    ready reference

53
OH story…
  • H2O ? H OH D0(H-OH)
  • OH ? O H D0(OH)
  • H2O ? O 2 H D0(H-OH) D0(OH) º DHat0(H2O)
    76720.7 8.3 cm-1
  • DHat(H2O) depends only on DHf(H2O), DHf(H),
    DHf(O)

D0(H-OH)
D0(OH)
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FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
56
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

Ruscic et al. 41128 24 cm-1
57
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

Ruscic et al. 41128 24 cm-1
Gurvich et al. 41301 17 cm-1
58
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
59
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
  • D0(HO-OH) 17051.8 3.4 cm-1 Luo, Fleming,
    Rizzo (1992) but to use it we would need to
    rely on ?Hf(H2O2)

60
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
  • D0(HO-OH) 17051.8 3.4 cm-1 Luo, Fleming,
    Rizzo (1992) but to use it we would need to
    rely on ?Hf(H2O2)
  • Joens (2001) D0(OH)/cm-1 ?Hf0(OH)/kcal/mol
  • Ruscic et al. (prelim. letter) 35600
    30 Þ 8.829 0.091
  • D0(H-OH) 41141 5 cm-1 Þ 35579 11 Þ 8.892
    ( 0.040)
  • D0(H2O2) 17051.8 3.4 cm-1 Þ 35589
    12 Þ 8.864 ( 0.042)
  • D 0.028
  • Þ 8.878 0.029

61
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
  • D0(HO-OH) 17051.8 3.4 cm-1 Luo, Fleming,
    Rizzo (1992) but to use it we would need to
    rely on ?Hf(H2O2)
  • Joens (2001) D0(OH)/cm-1 ?Hf0(OH)/kcal/mol
  • Ruscic et al. (prelim. letter) 35600
    30 Þ 8.829 0.091
  • D0(H-OH) 41141 5 cm-1 Þ 35579 11 Þ 8.892
    ( 0.040)
  • D0(H2O2) 17051.8 3.4 cm-1 Þ 35589
    12 Þ 8.864 ( 0.042)
  • D 0.028
  • Þ 8.878 0.029

?Hf0(H2O2) from JANAF (298.15 K selection
questionable, wrong conversion to 0 K)
62
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

5
23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
  • D0(HO-OH) 17051.8 3.4 cm-1 Luo, Fleming,
    Rizzo (1992) but to use it we would need to
    rely on ?Hf(H2O2)
  • Joens (2001) D0(OH)/cm-1 ?Hf0(OH)/kcal/mol
  • Ruscic et al. (prelim. letter) 35600
    30 Þ 8.829 0.091
  • D0(H-OH) 41141 5 cm-1 Þ 35579 11 Þ 8.892
    ( 0.040)
  • D0(H2O2) 17051.8 3.4 cm-1 Þ 35589
    12 Þ 8.864 ( 0.042)
  • D 0.028
  • Þ 8.878 0.029

4
?Hf0(H2O2) from JANAF (298.15 K selection
questionable, wrong conversion to 0 K)
63
FURTHER DEVELOPMENTS…
  • ?Hf0(OH) 8.86 0.16 kcal/mol Herbon, Hanson,
    Golden, Bowman (2002)

ü
Ruscic et al. 8.85 0.07 kcal/mol
  • D0(H-OH) 41151 5 cm-1 Harich, Hwang, Yang,
    Lin, Yang, Dixon (2000)

5
23 cm-1 (0.066 kcal/mol)
23.8 cm-1 100 000
Ruscic et al. 41128 24 cm-1
  • D0(HO-OH) 17051.8 3.4 cm-1 Luo, Fleming,
    Rizzo (1992) but to use it we would need to
    rely on ?Hf(H2O2)
  • Joens (2001) D0(OH)/cm-1 ?Hf0(OH)/kcal/mol
  • Ruscic et al. (prelim. letter) 35600
    30 Þ 8.829 0.091
  • D0(H-OH) 41141 5 cm-1 Þ 35579 11 Þ 8.892
    ( 0.040)
  • D0(H2O2) 17051.8 3.4 cm-1 Þ 35589
    12 Þ 8.864 ( 0.042)
  • D 0.028
  • Þ 8.878 0.029

4
8.920 0.018 8.855 0.027 0.065 8.900 0.381
?Hf0(H2O2) from JANAF (298.15 K selection
questionable, wrong conversion to 0 K)
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RESULTS OF ATcT O/H TN ANALYSIS
  • ?Hf0(OH) 8.859 0.017 kcal/mol (cf. Ruscic
    et al. 8.856 0.070 kcal/mol)
  • D0(H-OH) 41129 7 cm-1 (cf. Ruscic et
    al. 41128 24 cm-1)
  • D0(OH) 35590 12 cm-1 (cf. Ruscic et
    al. 35593 25 cm-1)
  • Statistical analysis points to the following
    optimistic uncertainties
  • D0(OH), Carlone Dalby 11.3 15 cm-1
  • D0(H-OH), Harich et al. 4.5 5 cm-1
  • DvapH298(H2O2), Edgerton et al. 2nd Law 1.4
    0.74 kcal/mol
  • D0(OH), Barrow 1.4 100 cm-1
  • DvapH298(H2O), Keenan et al., old steam tab.
    1.2 0.002 kcal/mol

78
ATcT HYPOTHESIS TEST (WHAT IF )
  • Hypothesis all photoionization experiments are
    off ? all AE0(OH/H2O) increased by 23.8 cm-1
  • Statistical analysis points to the following
    optimistic uncertainties
  • D0(OH), Carlone Dalby 11.2 15 cm-1
  • D0(H-OH), Harich et al. 4.1 5 cm-1
  • AE0(OH/H2O), PFI-PE Berkeley 1.5 0.002 eV
  • DvapH298(H2O2), Edgerton et al. 2nd Law 1.4
    0.74 kcal/mol
  • D0(OH), Barrow 1.4 100 cm-1
  • DvapH298(H2O), Keenan et al., old steam tab.
    1.2 0.002 kcal/mol
  • DvapH298(H2O2), Edgerton et al. 3rd Law 1.1
    0.038 kcal/mol

x Though the network does not allow the values to
stray away too much, this solution has to be
rejected because its based on a hypothesis
demonstrated to be incorrect
  • ?Hf0(OH) 8.863 0.009 kcal/mol (cf.
    unbiased ATcT 8.859 0.017 kcal/mol)
  • D0(H-OH) 41130 4 cm-1 (cf. unbiased
    ATcT 41129 7 cm-1)
  • D0(OH) 35588 6 cm-1 (cf. unbiased
    ATcT 35590 12 cm-1)

79
BOTTOM LINE…
JANAF
Gurvich et al.
Ruscic et al.
80
A few corollaries…H2O2
Gurvich et al.
JANAF
81
A few corollaries… O3
JANAF
Taniguchi et al
Gurvich et al.
82
A few corollaries… O3
JANAF
Taniguchi et al
Gurvich et al.
83
A few corollaries… O
CODATA, Gurvich et al., JANAF, …
84
A few corollaries… H
CODATA, Gurvich et al., JANAF, …
85
THE C (g) QUESTION
  • Its a 50-year old puzzle…
  • DfH(C(gas)) º DsublH(C(graphite))
  • DfH(C(gas)) is one of the CODATA key
    thermochemical quantities
  • Inter alia, it is used as a fixed reference point
    for carbon by all ab initio computations (such
    as Gn, Wn, etc) that produce enthalpies of
    formation via atomization energies
  • Early measurements attempted to
    determine DsublH(C(graphite)) via measurements
    of equilibria
  • CODATA used D0(CO), once it got settled…

86
THE C (g) QUESTION
The original D0(CO) is a weak link
87
THE D0(CO) QUESTION
  • A. E. Douglas and C. K. Moller, Can. J. Phys.
    33, 125 (1955)
  • The uncertainty addressed at the time was whether
    D0(CO) is 11.1 eV from apparent
    predissociation at v' 0, J gt 37 of the
    Ångström system of CO (B1S of A1P), or
    9.6 eV suggested by electron impact and
    supported by observed weakening of some lines at
    v 7, 8, 9 in the fourth positive system (A 1P
    of X1S) of CO or some yet different value

88
THE D0(CO) QUESTION
  • A. E. Douglas and C. K. Moller, Can. J. Phys.
    33, 125 (1955)
  • 12CO B1S predissociation clearly observed
    between J 37 and 38 in v 0 J 17 and 18
    in v 1 13CO B1S predissociation clearly
    observed between J 39 and 40 in v 0 J 19
    and 20 in v 1

D0(CO) 89595 30 cm-1
89
LIMITING CURVES OF DISSOCIATION of CO
CO B 1S
90
LIMITING CURVES OF DISSOCIATION of CO
CO B 1S
91
LIMITING CURVES OF DISSOCIATION of CO
CO B 1S
De(CO) 90739 30 cm-1 Þ D0(CO) 89660 30
cm-1
De(CO) 90739 30 cm-1 Þ D0(CO) 89660 30
cm-1 De(CO) 90677 30 cm-1 Þ D0(CO) 89595
30 cm-1
92
D0(CO)
  • From reinterpretation of spectroscopic data

De(CO) 90677 30 cm-1 Þ D0(CO) 89595 30
cm-1
De(CO) 90739 30 cm-1 Þ D0(CO) 89660 30
cm-1 (uncert. reflects a slight discrepancy
between 12CO and 13CO)
  • Best estimate from state of the art ab initio
    calculations (using converged levels of var.
    methods, including higher order coupled cluster
    and full configuration interaction benchmarks
    extrapolated to complete basis set full
    configuration interaction limit plus corrections
    for relativistic effects and diagonal
    Born-Oppenheimer correction to reduce remaining
    computational errors)

De(CO) 90758 30 cm-1 Þ D0(CO) 89679 30
cm-1
  • We are currently pursuing additional experiments
    at ALS in collaboration with C.-Y. Ng
    (measurements are in progress)

93
THE C (g) QUESTION
CODATA, Gurvich et al., JANAF, …
94
A couple of corollaries…
CODATA, Gurvich et al., JANAF, …
CODATA, Gurvich et al., JANAF, …
95
N
D0(N2), the primary determination leading to
DfH(N), is a weak link limiting the accuracy
of the thermochemistry of N and through it of
NOx species, as well as many other N-containing
species
CODATA, Gurvich et al., JANAF, …
96
NO AND NO2
Gurvich et al.
Gurvich et al.
JANAF
JANAF
97
HO2
Fisher Armentrout
Howard reaction OH NO2 HO2 NO
Ruscic Litorja
Lee Howard
Lineberger et al
Shum Benson
Gurvich et al.
ATcT thermo new kinetic experiments (J.
Michael, ANL) the reverse rate was indeed off by
a factor of 2!
JANAF
98
CH2O
Gurvich et al.
JANAF
99
HCO
Gurvich et al.
JANAF
100
CH4
Gurvich et al.
JANAF
101
CH3
Gurvich et al.
JANAF
102
CH2
Gurvich et al.
JANAF
103
CH
Gurvich et al.
JANAF
104
NH3
CODATA, JANAF, Gurvich et al
105
NH2
Gurvich et al.
JANAF
106
NH
JANAF
Gurvich et al.
107
Interplay of ATcT with Multi-Scale Chemical
Science
Chemical Mechanisms
  • - ATcT are a provider of information to other
    scales

Kinetic Rates
Working Groups
- ATcT are also a consumer of information from
other scales
ATcT
Molecular Scale
108
THE VISION STACKED ACTIVE TABLES
Reduced Mechanisms AT
Chemical Mechanisms AT
Kinetic Rates AT
ATcT
Spectro- scopic AT
Fundamental Constants AT
109
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