diff --git a/.Rbuildignore b/.Rbuildignore
index f5aa41f..9a2c1d3 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -15,3 +15,4 @@ README.Rmd
 ^Meta$
 ^cran-comments\.md$
 ^CRAN-SUBMISSION$
+^data-raw$
diff --git a/DESCRIPTION b/DESCRIPTION
index 763a016..6b8a755 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -46,4 +46,7 @@ biocViews:
 Config/testthat/edition: 3
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.3.1
+RoxygenNote: 7.3.2
+Depends: 
+    R (>= 2.10)
+LazyData: true
diff --git a/NEWS.md b/NEWS.md
index d5fce7b..fb6fbaf 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,6 +1,7 @@
 # volcalc (development version)
 
 * adds a `validate = TRUE` option to `calc_vol()` and `get_fx_groups()` that returns `NA`s when there are suspected errors in parsing SMILES or .mol files. This is unfortunately not available on Windows due to differences in the windows version of `ChemmineOB`
+* adds a dataset, `smarts_simpol1`, describing how functional groups are defined for the SIMPOL.1 and Meredith et al. methods
 
 # volcalc 2.1.2
 
diff --git a/R/data.R b/R/data.R
new file mode 100644
index 0000000..a056632
--- /dev/null
+++ b/R/data.R
@@ -0,0 +1,26 @@
+#' Search patterns used for SIMPOL.1 functional groups
+#'
+#' This dataframe documents how functional groups for the SIMPOL.1 and Meredith
+#' et al. method are defined using SMARTS strings or `ChemmineR` functions.
+#'
+#' @format
+#' \describe{
+#'   \item{method}{Either "simpol1" for functional groups only used with the SIMPOL.1 method, or "meredith" for additional groups used in the Meredith et al. method.}
+#'   \item{functional_groups}{These correspond to matching column names in the results of [get_fx_groups()].}
+#'   \item{description}{Functional group description from Table 5 of Pankow & Asher (2008)}
+#'   \item{smarts}{SMARTS strings used to capture groups, when applicable}
+#'   \item{fun}{The function used to capture the functional group.  When `smarts` is not `NA`, this is always "[ChemmineR::smartsSearchOB]".  Other groups are captured with other `ChemmineR` functions or as calculations using other functional groups.}
+#'   \item{notes}{Notes including how any functional group counts are corrected when there is overlap.  E.g. when one SMARTS pattern is a subset of another pattern, but the two groups are counted separately without overlap in the SIMPOL.1 method.}
+#' }
+#' 
+#' @references 
+#'   Meredith L, Ledford S, Riemer K, Geffre P, Graves K, Honeker L, LeBauer D,
+#'   Tfaily M, Krechmer J. 2023. Automating methods for estimating metabolite
+#'   volatility. Frontiers in Microbiology. \doi{10.3389/fmicb.2023.1267234}
+#'   
+#'   Pankow, J.F., Asher, W.E. 2008. SIMPOL.1: a simple group
+#'   contribution method for predicting vapor pressures and enthalpies of
+#'   vaporization of multifunctional organic compounds. Atmos. Chem. Phys.
+#'   \doi{10.5194/acp-8-2773-2008}
+#'   
+"smarts_simpol1"
\ No newline at end of file
diff --git a/R/get_fx_groups.R b/R/get_fx_groups.R
index e5f1161..822b4e1 100644
--- a/R/get_fx_groups.R
+++ b/R/get_fx_groups.R
@@ -17,13 +17,16 @@
 #'   risk! Validation is not available on Windows. See **Details** for more
 #'   information.
 #'   
-#' @details It is unfortunately difficult to capture errors and warnings
-#'   produced by the command line tool OpenBabel used by `ChemmineOB`, a
-#'   dependency of `volcalc`. These errors and warnings are printed to the R
-#'   console, but they are *not* R errors and do not stop code from running and
-#'   producing potentially incorrect data. `validate = TRUE` checks the output
-#'   of certain OpenBabel procedures for the *symptoms* of these errors, namely
-#'   missing values for InChI and molecular formula. Unfortunately, since InChI
+#' @details For more details on how functional groups are defined, see the
+#'   [smarts_simpol1] data set.
+#'
+#'   It is unfortunately difficult to capture errors and warnings produced by
+#'   the command line tool OpenBabel used by `ChemmineOB`, a dependency of
+#'   `volcalc`. These errors and warnings are printed to the R console, but they
+#'   are *not* R errors and do not stop code from running and producing
+#'   potentially incorrect data. `validate = TRUE` checks the output of certain
+#'   OpenBabel procedures for the *symptoms* of these errors, namely missing
+#'   values for InChI and molecular formula. Unfortunately, since InChI
 #'   generation is not available with the Windows version of `ChemmineOB`, this
 #'   validation step cannot be performed on Windows and `validate = TRUE` will
 #'   simply print a warning that can be silenced by setting `validate = FALSE`.
@@ -97,48 +100,7 @@ Set `validate = FALSE` to silence this warning.")
     carbon_dbl_count <- tibble::add_row(carbon_dbl_count, n = 0)
   }
   
-  # *_pattern are SMARTS strings: https://www.daylight.com/dayhtml_tutorials/languages/smarts/smarts_examples.html
-  carbon_dbl_bonds_pattern <- "C=C" #non-aromatic carbon double bonds
-  CCCO_pattern <- "C(C=C[AR1])(=O)[AR1]" #C=C-C=O in a non-aromatic ring
-  # ether_alkyl_pattern <- "[OD2]([C!R1])[C!R1]" #currently unused--ether_alkly calculated as total - other ethers
-  ether_alicyclic_pattern <- "[OD2]([C!R0])[C!R0]"
-  ether_aromatic_pattern <- "O(c)[C,c]" #only one of the carbons has to be aromatic
-  nitro_pattern <- "[$([NX3](=O)=O),$([NX3+](=O)[O-])][!#8]"
-  hydroxyl_aromatic_pattern <- "[OX2H]c"
-  nitrate_pattern <- "[$([NX3](=[OX1])(=[OX1])O),$([NX3+]([OX1-])(=[OX1])O)]"
-  
-  #TODO need patterns for amines that don't pick up amides
-  amine_primary_pattern <- "[NX3;H2;!$(NC=[!#6]);!$(NC#[!#6])][#6X4]"
-  amine_secondary_pattern <- "[NX3H1!$(NC=[!#6])!$(NC#[!#6])]([#6X4])[#6X4]"
-  amine_tertiary_pattern <- "[NX3H0!$(NC=[!#6])!$(NC#[!#6])]([#6X4])([#6X4])[#6X4]"
-  amine_aromatic_pattern <-  "[NX3;!$(NO)]c" 
-  
-  amide_primary_pattern <- "[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H2]"
-  amide_secondary_pattern <- "[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H1][#6;!$(C=[O,N,S])]"
-  amide_tertiary_pattern <- 
-    "[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H0]([#6;!$(C=[O,N,S])])[#6;!$(C=[O,N,S])]"
-  
-  # amide_total_pattern <- "[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3;$([H2]),$([H1][#6;!$(C=[O,N,S])]),$([#7]([#6;!$(C=[O,N,S])])[#6;!$(C=[O,N,S])])]"
-  
-  carbonylperoxynitrate_pattern <- "*C(=O)OO[N+1](=O)[O-1]"
-  peroxide_pattern <- "[OX2D2][OX2D2]"  #this captures carbonylperoxynitrates too
-  hydroperoxide_pattern <- "[OX2][OX2H,OX1-]" #this captures peroxyacids too
-  carbonylperoxyacid_pattern <- "[CX3;$([R0][#6]),$([H1R0])](=[OX1])[OX2][$([OX2H]),$([OX1-])]" 
-  nitroester_pattern <- "C(=O)(OC)C~[NX3](-,=[OX1])-,=[OX1]" 
-  # This captures OH groups on a ring that also has a nitro group (para, ortho, or meta).  Need to correct aromatic hydroxyl count later.
-  nitrophenol_pattern <- 
-    "[OX2H][$(c1ccccc1[$([NX3](=O)=O),$([NX3+](=O)[O-])]),$(c1cccc(c1)[$([NX3](=O)=O),$([NX3+](=O)[O-])]),$(c1ccc(cc1)[$([NX3](=O)=O),$([NX3+](=O)[O-])])]"
-  phosphoric_acid_pattern <-
-    "[$(P(=[OX1])([$([OX2H]),$([OX1-]),$([OX2]P)])([$([OX2H]),$([OX1-]),$([OX2]P)])[$([OX2H]),$([OX1-]),$([OX2]P)]),$([P+]([OX1-])([$([OX2H]),$([OX1-]),$([OX2]P)])([$([OX2H]),$([OX1-]),$([OX2]P)])[$([OX2H]),$([OX1-]),$([OX2]P)])]"
-  phosphoric_ester_pattern <-
-    "[$(P(=[OX1])([OX2][#6])([$([OX2H]),$([OX1-]),$([OX2][#6])])[$([OX2H]),$([OX1-]),$([OX2][#6]),$([OX2]P)]),$([P+]([OX1-])([OX2][#6])([$([OX2H]),$([OX1-]),$([OX2][#6])])[$([OX2H]),$([OX1-]),$([OX2][#6]),$([OX2]P)])]"
-  sulfate_pattern <-
-    "[$([#16X4](=[OX1])(=[OX1])([OX2H,OX1H0-])[OX2][#6]),$([#16X4+2]([OX1-])([OX1-])([OX2H,OX1H0-])[OX2][#6])]"
-  #sulfonate groups; sulfonate ions, and conjugate acid, sulfonic acids
-  sulfonate_pattern <-
-    "[#16X4](=[OX1])(=[OX1])([#6])[*$([O-1]),*$([OH1]),*$([OX2H0])]"
-  thiol_pattern <- "[#16X2H]"
-  carbothioester_pattern <- "S([#6])[CX3](=O)[#6]"
+  smarts <- smarts_patterns_simpol1
   
   fx_groups_df <- 
     dplyr::tibble(
@@ -154,43 +116,42 @@ Set `validate = FALSE` to silence this warning.")
       rings_aromatic = as.integer(rings$AROMATIC),
       rings_total = as.integer(rings$RINGS),
       rings_aliphatic = NA_integer_, #calculated below
-      carbon_dbl_bonds_aliphatic = ChemmineR::smartsSearchOB(compound_sdf, carbon_dbl_bonds_pattern),
-      CCCO_aliphatic_ring = ChemmineR::smartsSearchOB(compound_sdf, CCCO_pattern), # C=C-C=O in a non-aromatic ring
+      carbon_dbl_bonds_aliphatic = ChemmineR::smartsSearchOB(compound_sdf, smarts$carbon_dbl_bonds_aliphatic),
+      CCCO_aliphatic_ring = ChemmineR::smartsSearchOB(compound_sdf, smarts$CCCO_aliphatic_ring),
       hydroxyl_total = groups$ROH, 
-      hydroxyl_aromatic = ChemmineR::smartsSearchOB(compound_sdf, hydroxyl_aromatic_pattern, uniqueMatches = FALSE),
+      hydroxyl_aromatic = ChemmineR::smartsSearchOB(compound_sdf, smarts$hydroxyl_aromatic, uniqueMatches = FALSE),
       hydroxyl_aliphatic = NA_integer_, #calculated below
       aldehydes = groups$RCHO,
       ketones = groups$RCOR,
       carbox_acids = groups$RCOOH,
       ester = groups$RCOOR,
       ether_total = groups$ROR,
-      # ether_alkyl = ChemmineR::smartsSearchOB(compound_sdf, ether_alkyl_pattern),
-      ether_alkyl = NA_integer_,
-      ether_alicyclic = ChemmineR::smartsSearchOB(compound_sdf, ether_alicyclic_pattern),
-      ether_aromatic = ChemmineR::smartsSearchOB(compound_sdf, ether_aromatic_pattern),
-      nitrate = ChemmineR::smartsSearchOB(compound_sdf, nitrate_pattern),
-      nitro = ChemmineR::smartsSearchOB(compound_sdf, nitro_pattern),
-      amine_primary   = ChemmineR::smartsSearchOB(compound_sdf, amine_primary_pattern),
-      amine_secondary = ChemmineR::smartsSearchOB(compound_sdf, amine_secondary_pattern),
-      amine_tertiary  = ChemmineR::smartsSearchOB(compound_sdf, amine_tertiary_pattern),
-      amine_aromatic = ChemmineR::smartsSearchOB(compound_sdf, amine_aromatic_pattern),
-      amide_primary = ChemmineR::smartsSearchOB(compound_sdf, amide_primary_pattern),
-      amide_secondary = ChemmineR::smartsSearchOB(compound_sdf, amide_secondary_pattern),
-      amide_tertiary = ChemmineR::smartsSearchOB(compound_sdf, amide_tertiary_pattern),
-      carbonylperoxynitrate = ChemmineR::smartsSearchOB(compound_sdf, carbonylperoxynitrate_pattern),
-      peroxide = ChemmineR::smartsSearchOB(compound_sdf, peroxide_pattern),
-      hydroperoxide = ChemmineR::smartsSearchOB(compound_sdf, hydroperoxide_pattern),
-      carbonylperoxyacid = ChemmineR::smartsSearchOB(compound_sdf, carbonylperoxyacid_pattern),
-      nitrophenol = ChemmineR::smartsSearchOB(compound_sdf, nitrophenol_pattern),
-      nitroester = ChemmineR::smartsSearchOB(compound_sdf, nitroester_pattern),
+      ether_alkyl = NA_integer_, #calculated below
+      ether_alicyclic = ChemmineR::smartsSearchOB(compound_sdf, smarts$ether_alicyclic),
+      ether_aromatic = ChemmineR::smartsSearchOB(compound_sdf, smarts$ether_aromatic),
+      nitrate = ChemmineR::smartsSearchOB(compound_sdf, smarts$nitrate),
+      nitro = ChemmineR::smartsSearchOB(compound_sdf, smarts$nitro),
+      amine_primary   = ChemmineR::smartsSearchOB(compound_sdf, smarts$amine_primary),
+      amine_secondary = ChemmineR::smartsSearchOB(compound_sdf, smarts$amine_secondary),
+      amine_tertiary  = ChemmineR::smartsSearchOB(compound_sdf, smarts$amine_tertiary),
+      amine_aromatic = ChemmineR::smartsSearchOB(compound_sdf, smarts$amine_aromatic),
+      amide_primary = ChemmineR::smartsSearchOB(compound_sdf, smarts$amide_primary),
+      amide_secondary = ChemmineR::smartsSearchOB(compound_sdf, smarts$amide_secondary),
+      amide_tertiary = ChemmineR::smartsSearchOB(compound_sdf, smarts$amide_tertiary),
+      carbonylperoxynitrate = ChemmineR::smartsSearchOB(compound_sdf, smarts$carbonylperoxynitrate),
+      peroxide = ChemmineR::smartsSearchOB(compound_sdf, smarts$peroxide),
+      hydroperoxide = ChemmineR::smartsSearchOB(compound_sdf, smarts$hydroperoxide),
+      carbonylperoxyacid = ChemmineR::smartsSearchOB(compound_sdf, smarts$carbonylperoxyacid),
+      nitrophenol = ChemmineR::smartsSearchOB(compound_sdf, smarts$nitrophenol),
+      nitroester = ChemmineR::smartsSearchOB(compound_sdf, smarts$nitroester),
       
       # Additional groups from Meredith et al. 2023
-      phosphoric_acids = ChemmineR::smartsSearchOB(compound_sdf, phosphoric_acid_pattern),
-      phosphoric_esters = ChemmineR::smartsSearchOB(compound_sdf, phosphoric_ester_pattern),
-      sulfates = ChemmineR::smartsSearchOB(compound_sdf, sulfate_pattern),
-      sulfonates = ChemmineR::smartsSearchOB(compound_sdf, sulfonate_pattern),
-      thiols = ChemmineR::smartsSearchOB(compound_sdf, thiol_pattern),
-      carbothioesters = ChemmineR::smartsSearchOB(compound_sdf, carbothioester_pattern),
+      phosphoric_acids = ChemmineR::smartsSearchOB(compound_sdf, smarts$phosphoric_acids),
+      phosphoric_esters = ChemmineR::smartsSearchOB(compound_sdf, smarts$phosphoric_esters),
+      sulfates = ChemmineR::smartsSearchOB(compound_sdf, smarts$sulfates),
+      sulfonates = ChemmineR::smartsSearchOB(compound_sdf, smarts$sulfonates),
+      thiols = ChemmineR::smartsSearchOB(compound_sdf, smarts$thiols),
+      carbothioesters = ChemmineR::smartsSearchOB(compound_sdf, smarts$carbothioesters),
       oxygens   = atoms[["O"]] %||% 0L,
       chlorines = atoms[["Cl"]] %||% 0L,
       nitrogens = atoms[["N"]] %||% 0L,
diff --git a/R/sysdata.rda b/R/sysdata.rda
new file mode 100644
index 0000000..bb23864
Binary files /dev/null and b/R/sysdata.rda differ
diff --git a/data-raw/README.md b/data-raw/README.md
new file mode 100644
index 0000000..236cb11
--- /dev/null
+++ b/data-raw/README.md
@@ -0,0 +1,4 @@
+In the future, if new methods are added, create a separate .csv file named smarts_<method>.csv.
+To turn this into a user-facing dataset, edit `make_data.R` to add another `usethis::use_data()` and document it by adding a new entry to `R/data.R`.  To also use this in internal data, it needs to be added as an argument to `usethis::use_data(..., internal = TRUE)` since only one sysdata.rda can exist for holding internal data.  E.g. `usethis::use_data(smarts_patterns_simpol1, smarts_patterns_newmethod, internal = TRUE, overwrite = TRUE)`
+
+Be sure to run the code in `make_data.R` and to run `devtools::document()` to update data and documentation.
\ No newline at end of file
diff --git a/data-raw/make_data.R b/data-raw/make_data.R
new file mode 100644
index 0000000..65dcab0
--- /dev/null
+++ b/data-raw/make_data.R
@@ -0,0 +1,14 @@
+## code to prepare `smarts` dataset goes here
+smarts_simpol1 <- readr::read_csv("data-raw/smarts_simpol1.csv")
+
+#create user-facing data.frame
+usethis::use_data(smarts_simpol1, overwrite = TRUE)
+
+#create internal named list with just SMARTS strings
+just_smarts_simpol1 <- 
+  smarts_simpol1 %>% 
+  dplyr::filter(!is.na(smarts)) 
+smarts_patterns_simpol1 <- as.list(just_smarts_simpol1$smarts)
+names(smarts_patterns_simpol1) <- just_smarts_simpol1$functional_group
+
+usethis::use_data(smarts_patterns_simpol1, internal = TRUE, overwrite = TRUE)
diff --git a/data-raw/smarts_simpol1.csv b/data-raw/smarts_simpol1.csv
new file mode 100644
index 0000000..464f218
--- /dev/null
+++ b/data-raw/smarts_simpol1.csv
@@ -0,0 +1,39 @@
+method,functional_group,description,smarts,fun,notes
+simpol1,carbons_asa,carbon number on the acid-side of an amide,NA,NA,Not possible to capture with SMARTS
+simpol1,rings_aromatic,aromatic ring,NA,ChemmineR::rings,
+simpol1,rings_total,,NA,ChemmineR::rings,
+simpol1,rings_aliphatic,non-aromatic ring,NA,rings_total - rings_aromatic,
+simpol1,carbon_dbl_bonds_aliphatic,C=C (non-aromatic),C=C,ChemmineR::smartsSearchOB,
+simpol1,CCCO_aliphatic_ring,C=C-C=O in non-aromatic ring,C(C=C[AR1])(=O)[AR1],ChemmineR::smartsSearchOB,
+simpol1,hydroxyl_total,,NA,ChemmineR::groups,
+simpol1,hydroxyl_aromatic,"aromatic hydroxyl (e.g., phenol)",[OX2H]c,ChemmineR::smartsSearchOB,"This pattern also captures nitrophenols, so the number of nitrophenols is subtracted"
+simpol1,hydroxyl_aliphatic,hydroxyl (alkyl),NA,hydroxyl_total - hydroxyl_aromatic,
+simpol1,aldehydes,aldehyde,NA,ChemmineR::groups,
+simpol1,ketones,ketone,NA,ChemmineR::groups,
+simpol1,carbox_acids,carboxylic acid,NA,ChemmineR::groups,
+simpol1,ester,ester,NA,ChemmineR::groups,"This also captures carbonylperoxynitrates and nitroesters, so the number of carbonylperoxynitrates and nitroesters are subtracted"
+simpol1,ether_total,,NA,ChemmineR::groups,
+simpol1,ether_alkyl,ether,NA,ether_total - ether_alicyclic - ether_aromatic,
+simpol1,ether_alicyclic,ether (alicyclic),[OD2]([C!R0])[C!R0],ChemmineR::smartsSearchOB,
+simpol1,ether_aromatic,"ether, aromatic","O(c)[C,c]",ChemmineR::smartsSearchOB,Only one of the carbons has to be aromatic
+simpol1,nitrate,nitrate,"[$([NX3](=[OX1])(=[OX1])O),$([NX3+]([OX1-])(=[OX1])O)]",ChemmineR::smartsSearchOB,"This pattern also captures carbonylperoxynitrates, so the number of carbonylperoxynitrates is subtracted"
+simpol1,nitro,nitro,"[$([NX3](=O)=O),$([NX3+](=O)[O-])][!#8]",ChemmineR::smartsSearchOB,
+simpol1,amine_primary,"amine, primary",[NX3;H2;!$(NC=[!#6]);!$(NC#[!#6])][#6X4],ChemmineR::smartsSearchOB,
+simpol1,amine_secondary,"amine, secondary",[NX3H1!$(NC=[!#6])!$(NC#[!#6])]([#6X4])[#6X4],ChemmineR::smartsSearchOB,
+simpol1,amine_tertiary,"amine, tertiary",[NX3H0!$(NC=[!#6])!$(NC#[!#6])]([#6X4])([#6X4])[#6X4],ChemmineR::smartsSearchOB,
+simpol1,amine_aromatic,"amine, aromatic",[NX3;!$(NO)]c,ChemmineR::smartsSearchOB,
+simpol1,amide_primary,"amide, primary","[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H2]",ChemmineR::smartsSearchOB,
+simpol1,amide_secondary,"amide, secondary","[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H1][#6;!$(C=[O,N,S])]",ChemmineR::smartsSearchOB,
+simpol1,amide_tertiary,"amide, tertiary","[CX3;$([R0][#6]),$([H1R0])](=[OX1])[#7X3H0]([#6;!$(C=[O,N,S])])[#6;!$(C=[O,N,S])]",ChemmineR::smartsSearchOB,
+simpol1,carbonylperoxynitrate,carbonylperoxynitrate,*C(=O)OO[N+1](=O)[O-1],ChemmineR::smartsSearchOB,
+simpol1,peroxide,peroxide,[OX2D2][OX2D2],ChemmineR::smartsSearchOB,"This pattern also captures carbonylperoxynitrates, so the number of carbonylperoxinitrates is subtracted"
+simpol1,hydroperoxide,hydroperoxide,"[OX2][OX2H,OX1-]",ChemmineR::smartsSearchOB,"This pattern also captures peroxyacids, so the number of carbonylperoxyacids is subtracted"
+simpol1,carbonylperoxyacid,carbonylperoxyacid,"[CX3;$([R0][#6]),$([H1R0])](=[OX1])[OX2][$([OX2H]),$([OX1-])]",ChemmineR::smartsSearchOB,
+simpol1,nitrophenol,nitrophenol,"[OX2H][$(c1ccccc1[$([NX3](=O)=O),$([NX3+](=O)[O-])]),$(c1cccc(c1)[$([NX3](=O)=O),$([NX3+](=O)[O-])]),$(c1ccc(cc1)[$([NX3](=O)=O),$([NX3+](=O)[O-])])]",ChemmineR::smartsSearchOB,
+simpol1,nitroester,nitroester,"C(=O)(OC)C~[NX3](-,=[OX1])-,=[OX1]",ChemmineR::smartsSearchOB,"This pattern captures OH groups on a ring that also has a nitro group (para, ortho, or meta)"
+meredith,phosphoric_acids,,"[$(P(=[OX1])([$([OX2H]),$([OX1-]),$([OX2]P)])([$([OX2H]),$([OX1-]),$([OX2]P)])[$([OX2H]),$([OX1-]),$([OX2]P)]),$([P+]([OX1-])([$([OX2H]),$([OX1-]),$([OX2]P)])([$([OX2H]),$([OX1-]),$([OX2]P)])[$([OX2H]),$([OX1-]),$([OX2]P)])]",ChemmineR::smartsSearchOB,"This pattern also captures phosphoric esthers, so the number of phosphoric esters is subtracted"
+meredith,phosphoric_esters,,"[$(P(=[OX1])([OX2][#6])([$([OX2H]),$([OX1-]),$([OX2][#6])])[$([OX2H]),$([OX1-]),$([OX2][#6]),$([OX2]P)]),$([P+]([OX1-])([OX2][#6])([$([OX2H]),$([OX1-]),$([OX2][#6])])[$([OX2H]),$([OX1-]),$([OX2][#6]),$([OX2]P)])]",ChemmineR::smartsSearchOB,
+meredith,sulfates,,"[$([#16X4](=[OX1])(=[OX1])([OX2H,OX1H0-])[OX2][#6]),$([#16X4+2]([OX1-])([OX1-])([OX2H,OX1H0-])[OX2][#6])]",ChemmineR::smartsSearchOB,
+meredith,sulfonates,,"[#16X4](=[OX1])(=[OX1])([#6])[*$([O-1]),*$([OH1]),*$([OX2H0])]",ChemmineR::smartsSearchOB,This pattern captures sulfonate ions and their conjugate acids (sulfonic acids)
+meredith,thiols,,[#16X2H],ChemmineR::smartsSearchOB,
+meredith,carbothioesters,,S([#6])[CX3](=O)[#6],ChemmineR::smartsSearchOB,
diff --git a/data/smarts_simpol1.rda b/data/smarts_simpol1.rda
new file mode 100644
index 0000000..b6ff863
Binary files /dev/null and b/data/smarts_simpol1.rda differ
diff --git a/man/get_fx_groups.Rd b/man/get_fx_groups.Rd
index 41eadf6..dbd2c08 100644
--- a/man/get_fx_groups.Rd
+++ b/man/get_fx_groups.Rd
@@ -26,13 +26,16 @@ for specified compounds. Users will not typically interact with this function
 directly, but rather by using \code{\link[=calc_vol]{calc_vol()}}.
 }
 \details{
-It is unfortunately difficult to capture errors and warnings
-produced by the command line tool OpenBabel used by \code{ChemmineOB}, a
-dependency of \code{volcalc}. These errors and warnings are printed to the R
-console, but they are \emph{not} R errors and do not stop code from running and
-producing potentially incorrect data. \code{validate = TRUE} checks the output
-of certain OpenBabel procedures for the \emph{symptoms} of these errors, namely
-missing values for InChI and molecular formula. Unfortunately, since InChI
+For more details on how functional groups are defined, see the
+\link{smarts_simpol1} data set.
+
+It is unfortunately difficult to capture errors and warnings produced by
+the command line tool OpenBabel used by \code{ChemmineOB}, a dependency of
+\code{volcalc}. These errors and warnings are printed to the R console, but they
+are \emph{not} R errors and do not stop code from running and producing
+potentially incorrect data. \code{validate = TRUE} checks the output of certain
+OpenBabel procedures for the \emph{symptoms} of these errors, namely missing
+values for InChI and molecular formula. Unfortunately, since InChI
 generation is not available with the Windows version of \code{ChemmineOB}, this
 validation step cannot be performed on Windows and \code{validate = TRUE} will
 simply print a warning that can be silenced by setting \code{validate = FALSE}.
diff --git a/man/smarts_simpol1.Rd b/man/smarts_simpol1.Rd
new file mode 100644
index 0000000..f9e5534
--- /dev/null
+++ b/man/smarts_simpol1.Rd
@@ -0,0 +1,34 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/data.R
+\docType{data}
+\name{smarts_simpol1}
+\alias{smarts_simpol1}
+\title{Search patterns used for SIMPOL.1 functional groups}
+\format{
+\describe{
+\item{method}{Either "simpol1" for functional groups only used with the SIMPOL.1 method, or "meredith" for additional groups used in the Meredith et al. method.}
+\item{functional_groups}{These correspond to matching column names in the results of \code{\link[=get_fx_groups]{get_fx_groups()}}.}
+\item{description}{Functional group description from Table 5 of Pankow & Asher (2008)}
+\item{smarts}{SMARTS strings used to capture groups, when applicable}
+\item{fun}{The function used to capture the functional group.  When \code{smarts} is not \code{NA}, this is always "\link[ChemmineR:smartsSearchOB]{ChemmineR::smartsSearchOB}".  Other groups are captured with other \code{ChemmineR} functions or as calculations using other functional groups.}
+\item{notes}{Notes including how any functional group counts are corrected when there is overlap.  E.g. when one SMARTS pattern is a subset of another pattern, but the two groups are counted separately without overlap in the SIMPOL.1 method.}
+}
+}
+\usage{
+smarts_simpol1
+}
+\description{
+This dataframe documents how functional groups for the SIMPOL.1 and Meredith
+et al. method are defined using SMARTS strings or \code{ChemmineR} functions.
+}
+\references{
+Meredith L, Ledford S, Riemer K, Geffre P, Graves K, Honeker L, LeBauer D,
+Tfaily M, Krechmer J. 2023. Automating methods for estimating metabolite
+volatility. Frontiers in Microbiology. \doi{10.3389/fmicb.2023.1267234}
+
+Pankow, J.F., Asher, W.E. 2008. SIMPOL.1: a simple group
+contribution method for predicting vapor pressures and enthalpies of
+vaporization of multifunctional organic compounds. Atmos. Chem. Phys.
+\doi{10.5194/acp-8-2773-2008}
+}
+\keyword{datasets}