Esempio n. 1
0
    def readTopologyFile(self, tfile):
        """Reads _only_ the atom type definitions from a topology file. This is
        unnecessary for versions 36 and later of the CHARMM force field.

        Parameters
        ----------
        tfile : str
            : Name of the CHARMM TOPology file to read

        Notes
        -----
        The CHARMM TOPology file is also called a Residue Topology File
        """
        conv = CharmmParameterSet._convert
        if isinstance(tfile, str):
            own_handle = True
            f = CharmmFile(tfile)
        else:
            own_handle = False
            f = tfile
        for line in f:
            line = line.strip()
            if line[:4] != 'MASS': continue
            words = line.split()
            try:
                idx = conv(words[1], int, 'atom type')
                name = words[2]
                mass = conv(words[3], float, 'atom mass')
            except IndexError:
                raise CharmmFileError('Could not parse MASS section of %s' %
                                      tfile)
            # The parameter file might or might not have an element name
            try:
                elem = words[4]
                atomic_number = get_by_symbol(elem).atomic_number
            except (IndexError, KeyError):
                # Figure it out from the mass
                masselem = Element.getByMass(mass)
                if masselem is None:
                    atomic_number = 0  # Extra point or something
                else:
                    atomic_number = masselem.atomic_number
            atype = AtomType(name=name,
                             number=idx,
                             mass=mass,
                             atomic_number=atomic_number)
            self.atom_types_str[atype.name] = atype
            self.atom_types_int[atype.number] = atype
            self.atom_types_tuple[(atype.name, atype.number)] = atype
        if own_handle: f.close()
Esempio n. 2
0
    def readTopologyFile(self, tfile):
        """Reads _only_ the atom type definitions from a topology file. This is
        unnecessary for versions 36 and later of the CHARMM force field.

        Parameters
        ----------
        tfile : str
            : Name of the CHARMM TOPology file to read

        Notes
        -----
        The CHARMM TOPology file is also called a Residue Topology File
        """
        conv = CharmmParameterSet._convert
        if isinstance(tfile, str):
            own_handle = True
            f = CharmmFile(tfile)
        else:
            own_handle = False
            f = tfile
        for line in f:
            line = line.strip()
            if line[:4] != 'MASS': continue
            words = line.split()
            try:
                idx = conv(words[1], int, 'atom type')
                name = words[2]
                mass = conv(words[3], float, 'atom mass')
            except IndexError:
                raise CharmmFileError('Could not parse MASS section of %s' %
                                      tfile)
            # The parameter file might or might not have an element name
            try:
                elem = words[4]
                atomic_number = get_by_symbol(elem).atomic_number
            except (IndexError, KeyError):
                # Figure it out from the mass
                masselem = Element.getByMass(mass)
                if masselem is None:
                    atomic_number = 0 # Extra point or something
                else:
                    atomic_number = masselem.atomic_number
            atype = AtomType(name=name, number=idx, mass=mass,
                             atomic_number=atomic_number)
            self.atom_types_str[atype.name] = atype
            self.atom_types_int[atype.number] = atype
            self.atom_types_tuple[(atype.name, atype.number)] = atype
        if own_handle: f.close()
Esempio n. 3
0
    def readParameterFile(self, pfile):
        """
        Reads all of the parameters from a parameter file. Versions 36 and
        later of the CHARMM force field files have an ATOMS section defining
        all of the atom types.  Older versions need to load this information
        from the RTF/TOP files.

        Parameters:
            - pfile (str) : Name of the CHARMM PARameter file to read

        Notes: The atom types must all be loaded by the end of this routine.
        Either supply a PAR file with atom definitions in them or read in a
        RTF/TOP file first. Failure to do so will result in a raised
        RuntimeError.
        """
        conv = CharmmParameterSet._convert
        if isinstance(pfile, str):
            own_handle = True
            f = CharmmFile(pfile)
        else:
            own_handle = False
            f = pfile
        # What section are we parsing?
        section = None
        # The current cmap we are building (these span multiple lines)
        current_cmap = None
        current_cmap_data = []
        current_cmap_res = 0
        nonbonded_types = dict() # Holder
        parameterset = None
        read_first_nonbonded = False
        for line in f:
            line = line.strip()
            if not line:
                # This is a blank line
                continue
            if parameterset is None and line.strip().startswith('*>>'):
                parameterset = line.strip()[1:78]
                continue
            # Set section if this is a section header
            if line.startswith('ATOMS'):
                section = 'ATOMS'
                continue
            if line.startswith('BONDS'):
                section = 'BONDS'
                continue
            if line.startswith('ANGLES'):
                section = 'ANGLES'
                continue
            if line.startswith('DIHEDRALS'):
                section = 'DIHEDRALS'
                continue
            if line.startswith('IMPROPER'):
                section = 'IMPROPER'
                continue
            if line.startswith('CMAP'):
                section = 'CMAP'
                continue
            if line.startswith('NONBONDED'):
                read_first_nonbonded = False
                section = 'NONBONDED'
                continue
            if line.startswith('NBFIX'):
                section = 'NBFIX'
                continue
            if line.startswith('HBOND'):
                section = None
                continue
            # It seems like files? sections? can be terminated with 'END'
            if line.startswith('END'): # should this be case-insensitive?
                section = None
                continue
            # If we have no section, skip
            if section is None: continue
            # Now handle each section specifically
            if section == 'ATOMS':
                if not line.startswith('MASS'): continue # Should this happen?
                words = line.split()
                try:
                    idx = conv(words[1], int, 'atom type')
                    name = words[2]
                    mass = conv(words[3], float, 'atom mass')
                except IndexError:
                    raise CharmmFileError('Could not parse MASS section.')
                # The parameter file might or might not have an element name
                try:
                    elem = words[4]
                    atomic_number = get_by_symbol(elem).atomic_number
                except (IndexError, KeyError):
                    # Figure it out from the mass
                    masselem = Element.getByMass(mass)
                    if masselem is None:
                        atomic_number = 0 # Extra point or something
                    else:
                        atomic_number = masselem.atomic_number
                atype = AtomType(name=name, number=idx, mass=mass,
                                 atomic_number=atomic_number)
                self.atom_types_str[atype.name] = atype
                self.atom_types_int[atype.number] = atype
                self.atom_types_tuple[(atype.name, atype.number)] = atype
                continue
            if section == 'BONDS':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    k = conv(words[2], float, 'bond force constant')
                    req = conv(words[3], float, 'bond equilibrium dist')
                except IndexError:
                    raise CharmmFileError('Could not parse bonds.')
                key = (min(type1, type2), max(type1, type2))
                self.bond_types[key] = BondType(k, req)
                continue
            if section == 'ANGLES':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    k = conv(words[3], float, 'angle force constant')
                    theteq = conv(words[4], float, 'angle equilibrium value')
                except IndexError:
                    raise CharmmFileError('Could not parse angles.')
                key = (min(type1, type3), type2, max(type1, type3))
                self.angle_types[key] = AngleType(k, theteq)
                # See if we have a urey-bradley
                try:
                    ubk = conv(words[5], float, 'Urey-Bradley force constant')
                    ubeq = conv(words[6], float, 'Urey-Bradley equil. value')
                    ubtype = UreyBradleyType(ubk, ubeq)
                except IndexError:
                    ubtype = NoUreyBradley
                self.urey_bradley_types[key] = ubtype
                continue
            if section == 'DIHEDRALS':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    type4 = words[3]
                    k = conv(words[4], float, 'dihedral force constant')
                    n = conv(words[5], float, 'dihedral periodicity')
                    phase = conv(words[6], float, 'dihedral phase')
                except IndexError:
                    raise CharmmFileError('Could not parse dihedrals.')
                # Torsion can be in either direction. Sort by end groups first,
                # then sort by middle 2
                if type1 < type4:
                    key = (type1, type2, type3, type4)
                elif type1 > type4:
                    key = (type4, type3, type2, type1)
                else:
                    # OK, we need to sort by the middle atoms now
                    if type2 < type3:
                        key = (type1, type2, type3, type4)
                    else:
                        key = (type4, type3, type2, type1)
                # See if this is a second (or more) term of the dihedral group
                # that's already present.
                dihedral = DihedralType(k, n, phase)
                if key in self.dihedral_types:
                    # See if the existing dihedral type list has a term with
                    # the same periodicity -- If so, replace it
                    replaced = False
                    for i, dtype in enumerate(self.dihedral_types[key]):
                        if dtype.per == dihedral.per:
                            # Replace. Warn if they are different
                            if dtype != dihedral:
                                warnings.warn('Replacing dihedral %r with %r' % 
                                              (dtype, dihedral))
                            self.dihedral_types[key]
                            replaced = True
                            break
                    if not replaced:
                        self.dihedral_types[key].append(dihedral)
                else: # key not present
                    self.dihedral_types[key] = [dihedral]
                continue
            if section == 'IMPROPER':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    type4 = words[3]
                    k = conv(words[4], float, 'improper force constant')
                    theteq = conv(words[5], float, 'improper equil. value')
                except IndexError:
                    raise CharmmFileError('Could not parse dihedrals.')
                # If we have a 7th column, that is the real psi0 (and the 6th
                # is just a dummy 0)
                try:
                    tmp = conv(words[6], float, 'improper equil. value')
                    theteq = tmp
                except IndexError:
                    pass # Do nothing
                # Improper types seem not to have the central atom defined in
                # the first place, so just have the key a fully sorted list. We
                # still depend on the PSF having properly ordered improper atoms
                key = tuple(sorted([type1, type2, type3, type4]))
                self.improper_types[key] = ImproperType(k, theteq)
                continue
            if section == 'CMAP':
                # This is the most complicated part, since cmap parameters span
                # many lines. We won't do much error catching here.
                words = line.split()
                try:
                    holder = [float(w) for w in words]
                    current_cmap_data.extend(holder)
                except ValueError:
                    # We assume this is a definition of a new CMAP, so
                    # terminate the last CMAP if applicable
                    if current_cmap is not None:
                        # We have a map to terminate
                        ty = CmapType(current_cmap_res, current_cmap_data)
                        self.cmap_types[current_cmap] = ty
                    try:
                        type1 = words[0]
                        type2 = words[1]
                        type3 = words[2]
                        type4 = words[3]
                        type5 = words[4]
                        type6 = words[5]
                        type7 = words[6]
                        type8 = words[7]
                        res = conv(words[8], int, 'CMAP resolution')
                    except IndexError:
                        raise CharmmFileError('Could not parse CMAP data.')
                    # order the torsions independently
                    k1 = [type1, type2, type3, type4]
                    k2 = [type4, type3, type2, type1]
                    key1 = min(k1, k2)
                    k1 = [type5, type6, type7, type8]
                    k2 = [type8, type7, type6, type5]
                    key2 = min(k1, k2)
                    current_cmap = tuple(key1 + key2)
                    current_cmap_res = res
                    current_cmap_data = []
                continue
            if section == 'NONBONDED':
                # Now get the nonbonded values
                words = line.split()
                try:
                    atype = words[0]
                    # 1st column is ignored
                    epsilon = conv(words[2], float, 'vdW epsilon term')
                    rmin = conv(words[3], float, 'vdW Rmin/2 term')
                except IndexError:
                    # If we haven't read our first nonbonded term yet, we may
                    # just be parsing the settings that should be used. So
                    # soldier on
                    if not read_first_nonbonded: continue
                    raise CharmmFileError('Could not parse nonbonded terms.')
                except CharmmFileError as e:
                    if not read_first_nonbonded: continue
                    raise CharmmFileError(str(e))
                else:
                    # OK, we've read our first nonbonded section for sure now
                    read_first_nonbonded = True
                # See if we have 1-4 parameters
                try:
                    # 4th column is ignored
                    eps14 = conv(words[5], float, '1-4 vdW epsilon term')
                    rmin14 = conv(words[6], float, '1-4 vdW Rmin/2 term')
                except IndexError:
                    eps14 = rmin14 = None
                nonbonded_types[atype] = [epsilon, rmin, eps14, rmin14]
                continue
            if section == 'NBFIX':
                words = line.split()
                try:
                    at1 = words[0]
                    at2 = words[1]
                    emin = abs(conv(words[2], float, 'NBFIX Emin'))
                    rmin = conv(words[3], float, 'NBFIX Rmin')
                    try:
                        emin14 = abs(conv(words[4], float, 'NBFIX Emin 1-4'))
                        rmin14 = conv(words[5], float, 'NBFIX Rmin 1-4')
                    except IndexError:
                        emin14 = rmin14 = None
                    try:
                        self.atom_types_str[at1].add_nbfix(at2, rmin, emin,
                                                           rmin14, emin14)
                        self.atom_types_str[at2].add_nbfix(at1, rmin, emin,
                                                           rmin14, emin14)
                    except KeyError:
                        # Some stream files define NBFIX terms with an atom that
                        # is defined in another toppar file that does not
                        # necessarily have to be loaded. As a result, not every
                        # NBFIX found here will necessarily need to be applied.
                        # If we can't find a particular atom type, don't bother
                        # adding that nbfix and press on
                        pass
                except IndexError:
                    raise CharmmFileError('Could not parse NBFIX terms.')
                self.nbfix_types[(min(at1, at2), max(at1, at2))] = (emin, rmin)
        # If there were any CMAP terms stored in the parameter set, the last one
        # defined will not have been added to the set. Add it now.
        if current_cmap is not None:
            ty = CmapType(current_cmap_res, current_cmap_data)
            self.cmap_types[current_cmap] = ty
        # Now we're done. Load the nonbonded types into the relevant AtomType
        # instances. In order for this to work, all keys in nonbonded_types
        # must be in the self.atom_types_str dict. Raise a RuntimeError if this
        # is not satisfied
        try:
            for key in nonbonded_types:
                self.atom_types_str[key].set_lj_params(*nonbonded_types[key])
        except KeyError:
            raise RuntimeError('Atom type %s not present in AtomType list' %
                               key)
        if parameterset is not None: self.parametersets.append(parameterset)
        if own_handle: f.close()
Esempio n. 4
0
    def readParameterFile(self, pfile, permissive=False):
        """Reads all of the parameters from a parameter file. Versions 36 and later
        of the CHARMM force field files have an ATOMS section defining all of
        the atom types.  Older versions need to load this information from the
        RTF/TOP files.

        Parameters
        ----------
        pfile : str
            Name of the CHARMM PARameter file to read
        permissive : bool
            Accept non-bonbded parameters for undefined atom types (default:
            False).

        Notes
        -----
        The atom types must all be loaded by the end of this routine. Either
        supply a PAR file with atom definitions in them or read in a RTF/TOP
        file first. Failure to do so will result in a raised RuntimeError.
        """
        conv = CharmmParameterSet._convert
        if isinstance(pfile, str):
            own_handle = True
            f = CharmmFile(pfile)
        else:
            own_handle = False
            f = pfile
        # What section are we parsing?
        section = None
        # The current cmap we are building (these span multiple lines)
        current_cmap = None
        current_cmap_data = []
        current_cmap_res = 0
        nonbonded_types = dict()  # Holder
        parameterset = None
        read_first_nonbonded = False
        previous = ''
        for line in f:
            line = previous + line.strip()
            previous = ''
            if line.endswith('-'):
                # This will be continued on the next line.
                previous = line[:-1]
                continue
            if line.startswith('!'):
                # This is a comment.
                continue
            if not line:
                # This is a blank line
                continue
            if parameterset is None and line.strip().startswith('*>>'):
                parameterset = line.strip()[1:78]
                continue
            # Set section if this is a section header
            if line.startswith('ATOMS'):
                section = 'ATOMS'
                continue
            if line.startswith('BONDS'):
                section = 'BONDS'
                continue
            if line.startswith('ANGLES'):
                section = 'ANGLES'
                continue
            if line.startswith('DIHEDRALS'):
                section = 'DIHEDRALS'
                continue
            if line.startswith('IMPROPER'):
                section = 'IMPROPER'
                continue
            if line.startswith('CMAP'):
                section = 'CMAP'
                continue
            if line.startswith('NONBONDED'):
                read_first_nonbonded = False
                section = 'NONBONDED'
                fields = line.upper().split()
                if 'NBXMOD' in fields:
                    nbxmod = int(fields[fields.index('NBXMOD') + 1])
                    if nbxmod not in list(range(-5, 6)):
                        raise CharmmFileError(
                            'Unsupported value for NBXMOD: %d' % nbxmod)
                    self.nbxmod = nbxmod
                continue
            if line.startswith('NBFIX'):
                section = 'NBFIX'
                continue
            if line.startswith('THOLE'):
                section = 'NBTHOLE'
                continue
            if line.startswith('HBOND'):
                section = None
                continue
            # It seems like files? sections? can be terminated with 'END'
            if line.startswith('END'):  # should this be case-insensitive?
                section = None
                continue
            # If we have no section, skip
            if section is None: continue
            # Now handle each section specifically
            if section == 'ATOMS':
                if not line.startswith('MASS'): continue  # Should this happen?
                words = line.split()
                try:
                    idx = conv(words[1], int, 'atom type')
                    name = words[2]
                    mass = conv(words[3], float, 'atom mass')
                except IndexError:
                    raise CharmmFileError('Could not parse MASS section.')
                # The parameter file might or might not have an element name
                try:
                    elem = words[4]
                    atomic_number = get_by_symbol(elem).atomic_number
                except (IndexError, KeyError):
                    # Figure it out from the mass
                    masselem = Element.getByMass(mass)
                    if masselem is None:
                        atomic_number = 0  # Extra point or something
                    else:
                        atomic_number = masselem.atomic_number
                atype = AtomType(name=name,
                                 number=idx,
                                 mass=mass,
                                 atomic_number=atomic_number)
                self.atom_types_str[atype.name] = atype
                self.atom_types_int[atype.number] = atype
                self.atom_types_tuple[(atype.name, atype.number)] = atype
                continue
            if section == 'BONDS':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    k = conv(words[2], float, 'bond force constant')
                    req = conv(words[3], float, 'bond equilibrium dist')
                except IndexError:
                    raise CharmmFileError('Could not parse bonds.')
                key = (min(type1, type2), max(type1, type2))
                self.bond_types[key] = BondType(k, req)
                continue
            if section == 'ANGLES':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    k = conv(words[3], float, 'angle force constant')
                    theteq = conv(words[4], float, 'angle equilibrium value')
                except IndexError:
                    raise CharmmFileError('Could not parse angles.')
                key = (min(type1, type3), type2, max(type1, type3))
                self.angle_types[key] = AngleType(k, theteq)
                # See if we have a urey-bradley
                try:
                    ubk = conv(words[5], float, 'Urey-Bradley force constant')
                    ubeq = conv(words[6], float, 'Urey-Bradley equil. value')
                    ubtype = UreyBradleyType(ubk, ubeq)
                except IndexError:
                    ubtype = NoUreyBradley
                self.urey_bradley_types[key] = ubtype
                continue
            if section == 'DIHEDRALS':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    type4 = words[3]
                    k = conv(words[4], float, 'dihedral force constant')
                    n = conv(words[5], float, 'dihedral periodicity')
                    phase = conv(words[6], float, 'dihedral phase')
                except IndexError:
                    raise CharmmFileError('Could not parse dihedrals.')
                # Torsion can be in either direction. Sort by end groups first,
                # then sort by middle 2
                if type1 < type4:
                    key = (type1, type2, type3, type4)
                elif type1 > type4:
                    key = (type4, type3, type2, type1)
                else:
                    # OK, we need to sort by the middle atoms now
                    if type2 < type3:
                        key = (type1, type2, type3, type4)
                    else:
                        key = (type4, type3, type2, type1)
                # See if this is a second (or more) term of the dihedral group
                # that's already present.
                dihedral = DihedralType(k, n, phase)
                if key in self.dihedral_types:
                    # See if the existing dihedral type list has a term with
                    # the same periodicity -- If so, replace it
                    replaced = False
                    for i, dtype in enumerate(self.dihedral_types[key]):
                        if dtype.per == dihedral.per:
                            # Replace. Warn if they are different
                            if dtype != dihedral:
                                warnings.warn('Replacing dihedral %r with %r' %
                                              (dtype, dihedral))
                            self.dihedral_types[key]
                            replaced = True
                            break
                    if not replaced:
                        self.dihedral_types[key].append(dihedral)
                else:  # key not present
                    self.dihedral_types[key] = [dihedral]
                continue
            if section == 'IMPROPER':
                words = line.split()
                try:
                    type1 = words[0]
                    type2 = words[1]
                    type3 = words[2]
                    type4 = words[3]
                    k = conv(words[4], float, 'improper force constant')
                    theteq = conv(words[5], float, 'improper equil. value')
                except IndexError:
                    raise CharmmFileError('Could not parse dihedrals.')
                # If we have a 7th column, that is the real psi0 (and the 6th
                # is just a dummy 0)
                try:
                    tmp = conv(words[6], float, 'improper equil. value')
                    theteq = tmp
                except IndexError:
                    pass  # Do nothing
                # Improper types seem not to have the central atom defined in
                # the first place, so just have the key a fully sorted list. We
                # still depend on the PSF having properly ordered improper atoms
                key = tuple(sorted([type1, type2, type3, type4]))
                self.improper_types[key] = ImproperType(k, theteq)
                continue
            if section == 'CMAP':
                # This is the most complicated part, since cmap parameters span
                # many lines. We won't do much error catching here.
                words = line.split()
                try:
                    holder = [float(w) for w in words]
                    current_cmap_data.extend(holder)
                except ValueError:
                    # We assume this is a definition of a new CMAP, so
                    # terminate the last CMAP if applicable
                    if current_cmap is not None:
                        # We have a map to terminate
                        ty = CmapType(current_cmap_res, current_cmap_data)
                        self.cmap_types[current_cmap] = ty
                    try:
                        type1 = words[0]
                        type2 = words[1]
                        type3 = words[2]
                        type4 = words[3]
                        type5 = words[4]
                        type6 = words[5]
                        type7 = words[6]
                        type8 = words[7]
                        res = conv(words[8], int, 'CMAP resolution')
                    except IndexError:
                        raise CharmmFileError('Could not parse CMAP data.')
                    # order the torsions independently
                    k1 = [type1, type2, type3, type4]
                    k2 = [type4, type3, type2, type1]
                    key1 = min(k1, k2)
                    k1 = [type5, type6, type7, type8]
                    k2 = [type8, type7, type6, type5]
                    key2 = min(k1, k2)
                    current_cmap = tuple(key1 + key2)
                    current_cmap_res = res
                    current_cmap_data = []
                continue
            if section == 'NONBONDED':
                # Now get the nonbonded values
                words = line.split()
                try:
                    atype = words[0]
                    # 1st column is ignored
                    epsilon = conv(words[2], float, 'vdW epsilon term')
                    rmin = conv(words[3], float, 'vdW Rmin/2 term')
                except IndexError:
                    # If we haven't read our first nonbonded term yet, we may
                    # just be parsing the settings that should be used. So
                    # soldier on
                    if not read_first_nonbonded: continue
                    raise CharmmFileError('Could not parse nonbonded terms.')
                except CharmmFileError as e:
                    if not read_first_nonbonded: continue
                    raise CharmmFileError(str(e))
                else:
                    # OK, we've read our first nonbonded section for sure now
                    read_first_nonbonded = True
                # See if we have 1-4 parameters
                try:
                    # 4th column is ignored
                    eps14 = conv(words[5], float, '1-4 vdW epsilon term')
                    rmin14 = conv(words[6], float, '1-4 vdW Rmin/2 term')
                except IndexError:
                    eps14 = rmin14 = None
                nonbonded_types[atype] = [epsilon, rmin, eps14, rmin14]
                continue
            if section == 'NBFIX':
                words = line.split()
                try:
                    at1 = words[0]
                    at2 = words[1]
                    emin = abs(conv(words[2], float, 'NBFIX Emin'))
                    rmin = conv(words[3], float, 'NBFIX Rmin')
                    try:
                        emin14 = abs(conv(words[4], float, 'NBFIX Emin 1-4'))
                        rmin14 = conv(words[5], float, 'NBFIX Rmin 1-4')
                    except IndexError:
                        emin14 = rmin14 = None
                    try:
                        self.atom_types_str[at1].add_nbfix(
                            at2, rmin, emin, rmin14, emin14)
                        self.atom_types_str[at2].add_nbfix(
                            at1, rmin, emin, rmin14, emin14)
                    except KeyError:
                        # Some stream files define NBFIX terms with an atom that
                        # is defined in another toppar file that does not
                        # necessarily have to be loaded. As a result, not every
                        # NBFIX found here will necessarily need to be applied.
                        # If we can't find a particular atom type, don't bother
                        # adding that nbfix and press on
                        pass
                except IndexError:
                    raise CharmmFileError('Could not parse NBFIX terms.')
                self.nbfix_types[(min(at1, at2), max(at1, at2))] = (emin, rmin)
                continue
            # Here parse the possible nbthole section
            if section == 'NBTHOLE':
                words = line.split()
                try:
                    at1 = words[0]
                    at2 = words[1]
                    nbt = abs(conv(words[2], float, 'NBTHOLE a'))
                    try:
                        self.atom_types_str[at1].add_nbthole(at2, nbt)
                        self.atom_types_str[at2].add_nbthole(at1, nbt)
                    except KeyError:
                        pass
                except IndexError:
                    raise CharmmFileError('Could not parse NBTHOLE terms.')
                self.nbthole_types[(min(at1, at2), max(at1, at2))] = (nbt)
        # If there were any CMAP terms stored in the parameter set, the last one
        # defined will not have been added to the set. Add it now.
        if current_cmap is not None:
            ty = CmapType(current_cmap_res, current_cmap_data)
            self.cmap_types[current_cmap] = ty

        # If in permissive mode create an atomtype for every type used in
        # the nonbonded parameters. This is a work-around for when all that's
        # available is a CHARMM22 inp file, which has no ATOM/MASS fields

        if permissive:
            try:
                idx = max(self.atom_types_int.keys()) + 1000
            except ValueError:
                idx = 10000
            for key in nonbonded_types:
                if not key in self.atom_types_str:
                    atype = AtomType(name=key,
                                     number=idx,
                                     mass=float('NaN'),
                                     atomic_number=1)
                    self.atom_types_str[key] = atype
                    self.atom_types_int[idx] = atype
                    idx = idx + 1

        # Now we're done. Load the nonbonded types into the relevant AtomType
        # instances. In order for this to work, all keys in nonbonded_types
        # must be in the self.atom_types_str dict. Raise a RuntimeError if this
        # is not satisfied
        try:
            for key in nonbonded_types:
                self.atom_types_str[key].set_lj_params(*nonbonded_types[key])
        except KeyError:
            raise RuntimeError('Atom type %s not present in AtomType list' %
                               key)

        if parameterset is not None: self.parametersets.append(parameterset)
        if own_handle: f.close()