Data items in the ATOM_SITE category record details about the atom sites in a macromolecular crystal structure, such as the positional coordinates, atomic displacement parameters, magnetic moments and directions, and so on. The data items for describing anisotropic temperature or atomic displacement factors are only used if the corresponding items are not given in the ATOM_SITE_ANISOTROP category. Example 1 - based on PDB entry 5HVP and laboratory records for the structure corresponding to PDB entry 5HVP loop_ _atom_site.group_PDB _atom_site.type_symbol _atom_site.label_atom_id _atom_site.label_comp_id _atom_site.label_asym_id _atom_site.label_seq_id _atom_site.label_alt_id _atom_site.Cartn_x _atom_site.Cartn_y _atom_site.Cartn_z _atom_site.occupancy _atom_site.B_iso_or_equiv _atom_site.footnote_id _atom_site.auth_seq_id _atom_site.id ATOM N N VAL A 11 . 25.369 30.691 11.795 1.00 17.93 . 11 1 ATOM C CA VAL A 11 . 25.970 31.965 12.332 1.00 17.75 . 11 2 ATOM C C VAL A 11 . 25.569 32.010 13.808 1.00 17.83 . 11 3 ATOM O O VAL A 11 . 24.735 31.190 14.167 1.00 17.53 . 11 4 ATOM C CB VAL A 11 . 25.379 33.146 11.540 1.00 17.66 . 11 5 ATOM C CG1 VAL A 11 . 25.584 33.034 10.030 1.00 18.86 . 11 6 ATOM C CG2 VAL A 11 . 23.933 33.309 11.872 1.00 17.12 . 11 7 ATOM N N THR A 12 . 26.095 32.930 14.590 1.00 18.97 4 12 8 ATOM C CA THR A 12 . 25.734 32.995 16.032 1.00 19.80 4 12 9 ATOM C C THR A 12 . 24.695 34.106 16.113 1.00 20.92 4 12 10 ATOM O O THR A 12 . 24.869 35.118 15.421 1.00 21.84 4 12 11 ATOM C CB THR A 12 . 26.911 33.346 17.018 1.00 20.51 4 12 12 ATOM O OG1 THR A 12 3 27.946 33.921 16.183 0.50 20.29 4 12 13 ATOM O OG1 THR A 12 4 27.769 32.142 17.103 0.50 20.59 4 12 14 ATOM C CG2 THR A 12 3 27.418 32.181 17.878 0.50 20.47 4 12 15 ATOM C CG2 THR A 12 4 26.489 33.778 18.426 0.50 20.00 4 12 16 ATOM N N ILE A 13 . 23.664 33.855 16.884 1.00 22.08 . 13 17 ATOM C CA ILE A 13 . 22.623 34.850 17.093 1.00 23.44 . 13 18 ATOM C C ILE A 13 . 22.657 35.113 18.610 1.00 25.77 . 13 19 ATOM O O ILE A 13 . 23.123 34.250 19.406 1.00 26.28 . 13 20 ATOM C CB ILE A 13 . 21.236 34.463 16.492 1.00 22.67 . 13 21 ATOM C CG1 ILE A 13 . 20.478 33.469 17.371 1.00 22.14 . 13 22 ATOM C CG2 ILE A 13 . 21.357 33.986 15.016 1.00 21.75 . 13 23 # - - - - data truncated for brevity - - - - HETATM C C1 APS C . 1 4.171 29.012 7.116 0.58 17.27 1 300 101 HETATM C C2 APS C . 1 4.949 27.758 6.793 0.58 16.95 1 300 102 HETATM O O3 APS C . 1 4.800 26.678 7.393 0.58 16.85 1 300 103 HETATM N N4 APS C . 1 5.930 27.841 5.869 0.58 16.43 1 300 104 # - - - - data truncated for brevity - - - - Equivalent isotropic atomic displacement parameter, B~equiv~, in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters. B~equiv~ = (B~i~ B~j~ B~k~)^1/3^ B~n~ = the principal components of the orthogonalised B^ij^ The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.B_equiv_geom_mean. Isotropic temperature factor parameter, or equivalent isotropic temperature factor, B~equiv~, calculated from anisotropic temperature factor parameters. B~equiv~ = (1/3) sum~i~[sum~j~(B~ij~ A~i~ A~j~ a*~i~ a*~j~)] A = the real space cell lengths a* = the reciprocal space cell lengths B~ij~ = 8 pi^2^ U~ij~ Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44, 775-776. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.B_iso_or_equiv. The x atom site coordinate in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the description given in _atom_sites.Cartn_transform_axes. The estimated standard deviation of _atom_site.Cartn_x. The y atom site coordinate in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the description given in _atom_sites.Cartn_transform_axes. The estimated standard deviation of _atom_site.Cartn_y. The z atom site coordinate in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the description given in _atom_sites.Cartn_transform_axes. The estimated standard deviation of _atom_site.Cartn_z. Equivalent isotropic atomic displacement parameter, U~equiv~, in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters. U~equiv~ = (U~i~ U~j~ U~k~)^1/3^ U~n~ = the principal components of the orthogonalised U~ij~ The estimated standard deviation of _atom_site.U_equiv_geom_mean. Isotropic atomic displacement parameter, or equivalent isotropic atomic displacement parameter, U~equiv~, calculated from anisotropic atomic displacement parameters. U~equiv~ = (1/3) sum~i~[sum~j~(U~ij~ A~i~ A~j~ a*~i~ a*~j~)] A = the real space cell lengths a* = the reciprocal space cell lengths Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44, 775-776. The estimated standard deviation of _atom_site.U_iso_or_equiv. The Wyckoff symbol (letter) as listed in the space-group section of International Tables for Crystallography, Vol. A (1987). The [1][1] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[1][1]. The [1][2] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[1][2]. The [1][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[1][3]. The [2][2] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[2][2]. The [2][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[2][3]. The [3][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site.aniso_B[3][3]. The [1][1] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[1][1]. The [1][2] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[1][2]. The [1][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[1][3]. The [2][2] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[2][2]. The [2][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[2][3]. The [3][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site.aniso_U[3][3]. Ratio of the maximum to minimum principal axes of displacement (thermal) ellipsoids. The number of hydrogen atoms attached to the atom at this site excluding any H atoms for which coordinates (measured or calculated) are given. water oxygen 2 hydroxyl oxygen 1 ammonium nitrogen 4 An alternative identifier for _atom_site.label_asym_id that may be provided by an author in order to match the identification used in the publication that describes the structure. An alternative identifier for _atom_site.label_atom_id that may be provided by an author in order to match the identification used in the publication that describes the structure. An alternative identifier for _atom_site.label_comp_id that may be provided by an author in order to match the identification used in the publication that describes the structure. An alternative identifier for _atom_site.label_seq_id that may be provided by an author in order to match the identification used in the publication that describes the structure. Note that this is not necessarily a number, that the values do not have to be positive, and that the value does not have to correspond to the value of _atom_site.label_seq_id. The value of _atom_site.label_seq_id is required to be a sequential list of positive integers. The author may assign values to _atom_site.auth_seq_id in any desired way. For instance, the values may be used to relate this structure to a numbering scheme in a homologous structure, including sequence gaps or insertion codes. Alternatively, a scheme may be used for a truncated polymer that maintains the numbering scheme of the full length polymer. In all cases, the scheme used here must match the scheme used in the publication that describes the structure. The _atom_site.id of the atom site to which the 'geometry- calculated' atom site is attached. A standard code to signal if the site data have been determined from the intensities or calculated from the geometry of surrounding sites, or have been assigned dummy coordinates. The abbreviation 'c' may be used in place of 'calc'. This data item is a pointer to _chemical_conn_atom.number in the CHEMICAL_CONN_ATOM category. A description of the constraints applied to parameters at this site during refinement. See also _atom_site.refinement_flags and _refine.ls_number_constraints. pop=1.0-pop(Zn3) A description of special aspects of this site. See also _atom_site.refinement_flags. Ag/Si disordered A code which identifies a cluster of atoms that show long-range positional disorder but are locally ordered. Within each such cluster of atoms, _atom_site.disorder_group is used to identify the sites that are simultaneously occupied. This field is only needed if there is more than one cluster of disordered atoms showing independent local order. *** This data item would not in general be used in a macromolecular data block. *** A code that identifies a group of positionally disordered atom sites that are locally simultaneously occupied. Atoms that are positionally disordered over two or more sites (e.g. the H atoms of a methyl group that exists in two orientations) can be assigned to two or more groups. Sites belonging to the same group are simultaneously occupied, but those belonging to different groups are not. A minus prefix (e.g. "-1") is used to indicate sites disordered about a special position. *** This data item would not in general be used in a macromolecular data block. *** The value of _atom_site.footnote_id must match an id specified by _atom_sites_footnote.id in the ATOM_SITES_FOOTNOTE list. The x coordinate of the atom site position specified as a fraction of _cell.length_a. The estimated standard deviation of _atom_site.fract_x. The y coordinate of the atom site position specified as a fraction of _cell.length_b. The estimated standard deviation of _atom_site.fract_y. The z coordinate of the atom site position specified as a fraction of _cell.length_c. The estimated standard deviation of _atom_site.fract_z. The group of atoms to which the atom site belongs. This data item is provided for compatibility with the original Protein Data Bank format, and only for that purpose. A component of the macromolecular identifier for this atom site. For further details, see the definition of the ATOM_SITE_ALT category. This data item is a pointer to _atom_sites_alt.id in the ATOM_SITES_ALT category. A component of the macromolecular identifier for this atom site. For further details, see the definition of the STRUCT_ASYM category. This data item is a pointer to _struct_asym.id in the STRUCT_ASYM category. A component of the macromolecular identifier for this atom site. This data item is a pointer to _chem_comp_atom.atom_id in the CHEM_COMP_ATOM category. A component of the macromolecular identifier for this atom site. This data item is a pointer to _chem_comp.id in the CHEM_COMP category. This data item is a pointer to _entity.id in the ENTITY category. This data item is a pointer to _entity_poly_seq.num in the ENTITY_POLY_SEQ category. The fraction of the atom type present at this site. The sum of the occupancies of all the atom types at this site may not significantly exceed 1.0 unless it is a dummy site. The estimated standard deviation of _atom_site.occupancy. PDB atom name. PDB insertion code. PDB model number. PDB residue name. PDB residue number. PDB strand id. Author's alternate location identifier. Author's atom name. A concatenated series of single-letter codes which indicate the refinement restraints or constraints applied to this site. A description of restraints applied to specific parameters at this site during refinement. See also _atom_site.refinement_flags and _refine.ls_number_restraints. restrained to planar ring The multiplicity of a site due to the space-group symmetry as is given in International Tables for Crystallography, Vol. A (1987). A standard code used to describe the type of atomic displacement parameters used for the site. This data item is a pointer to _atom_type.symbol in the ATOM_TYPE category. The value of _atom_site.id must uniquely identify a record in the ATOM_SITE list. Note that this item need not be a number; it can be any unique identifier. This data item was introduced to facilitate compatibility between small molecule and macromolecular files. In the small molecule files, _atom_site_label is the identifier for the atom. In the macromolecular files, the atom identifier is the aggregate of _atom_site.label_alt_id, _atom_site.label_asym_id, _atom_site.label_atom_id, _atom_site.label_comp_id and _atom_site.label_seq_id. For the two types of files to be compatible, a formal identifier for the category had to be introduced that was independent of the different modes of identifying atoms. For compatibility with older files, _atom_site_label is aliased to _atom_site.id. 5 C12 Ca3g28 Fe3+17 H*251 boron2a C_a_phe_83_a_0 Zn_Zn_301_A_0 Data items in the ATOM_SITE_ANISOTROP category record details about temperature or thermal displacement factors, if those data items are contained in a separate list from the ATOM_SITE list. If the ATOM_SITE_ANISOTROP category is used for storing these data, the corresponding ATOM_SITE data items are not used. Example 1 - based on NDB structure BDL005 of Holbrook, Dickerson & Kim [(1985). Acta Cryst. B41, 255-262]. loop_ _atom_site_anisotrop.id _atom_site_anisotrop.type_symbol _atom_site_anisotrop.U[1][1] _atom_site_anisotrop.U[1][2] _atom_site_anisotrop.U[1][3] _atom_site_anisotrop.U[2][2] _atom_site_anisotrop.U[2][3] _atom_site_anisotrop.U[3][3] 1 O 8642 4866 7299 -342 -258 -1427 2 C 5174 4871 6243 -1885 -2051 -1377 3 C 6202 5020 4395 -1130 -556 -632 4 O 4224 4700 5046 1105 -161 345 5 C 8684 4688 4171 -1850 -433 -292 6 O 11226 5255 3532 -341 2685 1328 7 C 10214 2428 5614 -2610 -1940 902 8 C 4590 3488 5827 751 -770 986 9 N 5014 4434 3447 -17 -1593 539 # ---- abbreviated ---- The [1][1] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[1][1]. The [1][2] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[1][2]. The [1][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[1][3]. The [2][2] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[2][2]. The [2][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[2][3]. The [3][3] element of the anisotropic atomic displacement matrix B, which appears in the structure factor term as: T = exp{-1/4 sum~i~[sum~j~(B~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred. The estimated standard deviation of _atom_site_anisotrop.B[3][3]. The [1][1] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[1][1]. The [1][2] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[1][2]. The [1][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[1][3]. The [2][2] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[2][2]. The [2][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[2][3]. The [3][3] element of the standard anisotropic atomic displacement matrix U, which appears in the structure factor term as: T = exp{-2 pi^2^ sum~i~[sum~j~(U~ij~ h~i~ h~j~ a*~i~ a*~j~)]} h = the Miller indices a* = the reciprocal space cell lengths These matrix elements may appear with atomic coordinates in the ATOM_SITE category, or they may appear in the separate ATOM_SITE_ANISOTROP category, but they may not appear in both places. Similarly, anisotropic displacements may appear as either B's or U's, but not as both. The unique elements of the real symmetric matrix are entered by row. The estimated standard deviation of _atom_site_anisotrop.U[3][3]. Pointer to _atom_site.pdbx_PDB_ins_code Pointer to _atom_site.pdbx_auth_alt_id. Pointer to _atom_site.auth_asym_id Pointer to _atom_site.auth_atom_id Pointer to _atom_site.auth_comp_id Pointer to _atom_site.auth_seq_id Pointer to _atom_site.label_alt_id. Pointer to _atom_site.label_asym_id Pointer to _atom_site.label_atom_id Pointer to _atom_site.label_comp_id Pointer to _atom_site.label_seq_id Ratio of the maximum to minimum principal axes of displacement (thermal) ellipsoids. This data item is a pointer to _atom_type.symbol in the ATOM_TYPE category. This data item is a pointer to _atom_site.id in the ATOM_SITE category. Data items in the ATOM_SITES category record details about the crystallographic cell and cell transformations, which are common to all atom sites. Example 1 - based on PDB entry 5HVP and/or laboratory records for the structure corresponding to PDB entry 5HVP _atom_sites.entry_id '5HVP' _atom_sites.Cartn_transform_axes 'c along z, astar along x, b along y' _atom_sites.Cartn_transf_matrix[1][1] 58.39 _atom_sites.Cartn_transf_matrix[1][2] 0.00 _atom_sites.Cartn_transf_matrix[1][3] 0.00 _atom_sites.Cartn_transf_matrix[2][1] 0.00 _atom_sites.Cartn_transf_matrix[2][2] 86.70 _atom_sites.Cartn_transf_matrix[2][3] 0.00 _atom_sites.Cartn_transf_matrix[3][1] 0.00 _atom_sites.Cartn_transf_matrix[3][2] 0.00 _atom_sites.Cartn_transf_matrix[3][3] 46.27 _atom_sites.Cartn_transf_vector[1] 0.00 _atom_sites.Cartn_transf_vector[2] 0.00 _atom_sites.Cartn_transf_vector[3] 0.00 The [1][1] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [1][2] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [1][3] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [2][1] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [2][2] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [2][3] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3| The [3][1] element of the 3x3 matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates in the same category. The axial alignments of this transformation are described in _atom_sites.Cartn_transform_axes. The 3x1 translation is defined in _atom_sites.Cartn_transf_vector[]. |x'| |11 12 13| |x| |1| |y'|~Cartesian~ = |21 22 23| |y|~fractional~ + |2| |z'| |31 32 33| |z| |3|