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Second round of proposed changes
- To: Multiple recipients of list <coredmg@iucr.org>
- Subject: Second round of proposed changes
- From: "I. David Brown" <idbrown@mcmail.cis.mcmaster.ca>
- Date: Fri, 27 Sep 2002 19:26:50 +0100 (BST)
Dear Colleagues,
Having had no response to my message of Sept 9 opening
discussion on the proposed changes to the atom_site and
atom_sites categories of the core CIF dictionary, and in
accordance with the assumption spelled out in that message, these
proposals are unanimously approved by the Dictionary Maintenance
Group (DMG). I have therefore marked these as approved in the
master list and we can now move us on to the next two categories:
cell and chemical.
Please can I have some response, particularly from the
members of the DMG, so that I know that people are receiving and
reading this email? Your silence will not be considered an
abstention but will be interpreted as a positive approval of the
changes. If you have any reservations about these items, let me
know and I will remove them for further study. Otherwise these
17 items will be added to the list of approved new (or modified)
datanames.
Please respond by 14 October.
Best wishes
David
##################################################
#
# PROPOSED NEW DEFINITIONS FOR CIF_CORE_2.3.DIC
#
##################################################
#
# Contents of this email
#
# CELL
# _cell_reciprocal_angle_alpha
# _cell_reciprocal_angle_beta
# _cell_reciprocal_angle_gamma
# _cell_formula_units_Z
# _cell_reciprocal_length_a
# _cell_reciprocal_length_b
# _cell_reciprocal_length_c
# CHEMICAL
# _chemical_melting_point_gt
# _chemical_melting_point_lt
# _chemical_properties_biological
# _chemical_properties_physical
# _chemical_temperature_decomposition
# _chemical_temperature_decomposition_gt
# _chemical_temperature_decomposition_lt
# _chemical_temperature_sublimation
# _chemical_temperature_sublimation_gt
# _chemical_temperature_sublimation_lt
##################################################
#
# CELL category
#
##################################################
data_cell_reciprocal_angle_
loop_ _name '_cell_reciprocal_angle_alpha'
'_cell_reciprocal_angle_beta'
'_cell_reciprocal_angle_gamma'
_category cell
_type numb
_type_conditions esd
_enumeration_range 0.0:180.0
_enumeration_default 90.0
_units deg
_units_detail 'degrees'
_definition
;
The angles defining the reciprocal cell. These are related to
those in the real cell by:
cos(recip-alpha) = (cos(beta)*cos(gamma) - cos(alpha))/(sin(beta)*sin(gamma))
cos(recip-beta) = (cos(gamma)*cos(alpha) - cos(beta))/(sin(gamma)*sin(alpha))
cos(recip-gamma) = (cos(alpha)*cos(beta) - cos(gamma))/(sin(alpha)*sin(beta))
(M.J.Buerger: X-ray Crystallography; New York, John Wiley & Sons Inc;
1942 p.360)
;
# COMMENT: Requested by CCDC
# STATUS: Open for discussion
data_cell_formula_units_Z_prime
_name '_cell_formula_units_Z'
_category cell
_type numb
_enumeration_range 1:
_definition
; The number of the formula units as specified
by _chemical_formula_structural, _chemical_formula_moiety or
_chemical_formula_sum in the asymmetric unit of the
unit cell given in the CELL category and the
space group defined in the SYMMETRY or SPACE GROUP category.
;
# COMMENT: Requested by CCDC
# STATUS: Open for discussion
data_cell_reciprocal_length_
loop_ _name '_cell_recirpocal_length_a'
'_cell_reciprocal_length_b'
'_cell_reciprocal_length_c'
_category cell
_type numb
_type_conditions esd
_enumeration_range 0.0:
_units A^-1^
_units_detail 'reciprocal angstroms'
_definition
;
The reciprocal cell lengths in inverse Angstroms. These are
related to the real cell by the following equation:
recip-a = b*c*sin(alpha)/V
recip-b = c*a*sin(beta)/V
recip-c = a*b*sin(gamma)/V
where V is the cell volume. (M.J.Buerger: X-ray Crystallography;
New York, John Wiley & Sons Inc; 1942 p.360)
;
# COMMENT: Requested by CCDC
# STATUS: Open for discussion
###################################################
#
# CHEMICAL category
#
###################################################
data_chemical_melting_point_lt
_name '_chemical_melting_point_lt'
_category chemical
_type numb
_enumeration_range 0.0:
_units K
_units_detail 'Kelvins'
_definition
; A temperature in Kelvins which represents an upper limit to
the melting point, the temperature at which a crystalline solid
changes to a liquid.
;
# COMMENT: Introduced to allow for a maximum limit or range of temperatures to
# be given.
# Note that _chemical_melting_point should have the _type_conditions of 'esd'
# added
# STATUS: Open for discussion
data_chemical_melting_point_gt
_name '_chemical_melting_point_gt'
_category chemical
_type numb
_enumeration_range 0.0:
_units K
_units_detail 'Kelvins'
_definition
; A temperature in Kelvin which represents a lower limit to the
melting point, the temperature at which a crystalline
solid changes to a liquid.
;
# COMMENT: See previous item
# STATUS: Open for discussion
data__chemcial_properties_biological
_name '_chemcial_properties_biological'
_category chemical
_type char
_example ?
_definition
; A free description of the biological properties of the
material.
;
# COMMENT: Suggested by CCDC for comments found in the CSD
# STATUS: Open for discussion
data_chemcial_properties_physical
_name '_chemcial_properties_physical'
_category chemical
_type char
_example ?
_definition
; A free description of the physical properties of the material.
;
# COMMENT: Suggested by CCDC for comments found in the CSD
# STATUS: Open for discussion
data_chemical_temperature_decomposition
_name '_chemical_temperature_decomposition'
_category chemical
_type numb
_type_conditions esd
_units K
_units_detail Kelvin
_example 350
_definition
; The temperature in Kelvin at which a solid decomposes.
;
# COMMENT: Suggested by CCDC.
# STATUS: Open for discussion
data_chemical_temperature_decomposition_*
loop_ _name '_chemical_temperature_decomposition_gt'
'_chemical_temperature_decomposition_lt'
_category chemical
_type numb
_units K
_units_detail Kelvin
_example 350
_definition
; *_lt is a temperature below which the solid is known
to decompose, *_gt is the a temperature above which
the solid is known to decompose.
;
# COMMENT: Suggested by CCDC. These two items allow a range of
# temperatures to be specified.
# STATUS: Open for discussion
data_chemical_temperature_sublimation
_name '_chemical_temperature_sublimation'
_category chemical
_type numb
_type_conditions esd
_units K
_units_detail Kelvin
_example 350
_definition
; The temperature in Kelvin at which a solid sublimes.
;
# COMMENT: Suggested by CCDC.
# STATUS: Open for discussion
data_chemical_temperature_sublimation_*
loop_ _name '_chemical_temperature_sublimation_gt'
'_chemical_temperature_sublimation_lt'
_category chemical
_type numb
_units K
_units_detail Kelvin
_example 350
_definition
; *_lt is a temperature below which the solid is known to
sublime, *_gt is the a temperature above which the solid
is known to sublime.
;
# COMMENT: Suggested by CCDC. These two items allow a range of temperatures
# to be specified.
# STATUS: Open for discussion
*****************************************************
Dr.I.David Brown, Professor Emeritus
Brockhouse Institute for Materials Research,
McMaster University, Hamilton, Ontario, Canada
Tel: 1-(905)-525-9140 ext 24710
Fax: 1-(905)-521-2773
idbrown@mcmaster.ca
*****************************************************
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