PROGRAM SNPLSQ

Least squares refinement from magnetic structure factor data

Description:

Main program for least squares refinement, of magnetic structure factor data from (possibly) mixed nuclear and magnetic reflections the magnetic symmetry can less than the nuclear symmetry. Can conbine
SNP, intensity and flipping ratio data

Input:

The crystal data file must contain all cards needed for magnetic and nuclear structure factor calculations vis:

S cards giving the symmetry.
A C card with the cell dimensions.
A cards defining the atoms, their positions and isotropic. temperature factors.
F cards giving the magnetic and non-magnetic scattering factors
Q cards defining the magnetic structure
R cards giving twin matrices if the magnetic structure can't be generated using all the symmetry elements of the structure group, even allowing NSYM type operations leading to s-domains. One R TMAT for each missing operator

optionally:

T cards giving anisotropic temperature factors

Additionally:

L cards indicating which parameters should be refined

(see the CCSL users' manual)

L DATA <ID> <Fname> cards giving the data idedtifier ID and filename

for each data source

L SORC ID REFI <iref> IType of refinement for source ID

REFI= 1 Refine on mod(Fc)
REFI= 2 Refine on Fc squared
REFI= 4 Refine on signed Fc
REFI= 5 Refine on polarised neutron Flipping Ratios
REFI= 6 Refine on ratio of magnetic to nuclear structure factors
REFI= 7 Refine on Polarized neutron intensity asymmetry
REFI= 8 Refine on elements of the polarisation matrix SNP

L SORC ID MODE <Moder> format of data source ID

(may be on the same card as REFI ans/or WGHT).

L SORC ID WGHT <Moder> relative weight to be given to data ID

(may be on the same card as REFI and/or MODE)

L SORC ID SCAL <Scales> scale factors for source ID as many as

required (may terminate the same card as REFI or MODE, start or continue on a different L SORC I D SCAL card with the same ID.

L SORC ID DPOP <Dpops> domain populations for source ID; as many as

required (may terminate the same card as REFI or MODE, start or continue on a different L SORC I D DPOP card with the same ID.

I cards which may have the words words NCYC, CYCL1, PRIN,

MCOR and CONV
NCYC the number of least squares cycles (default 3)
CYC1 the number to be assigned to the first cycle (default 1)
PRIN frequency at which output lists are printed

PRIN = 0 no printing
PRIN = 1 first cycle
PRIN = 2 last cycle
PRIN = 3 first and last cycles
PRIN = 4 every cycle

MCOR controls the correlations printed at the end of the job

(default +70)
MCOR = 0 whole correlation matrix printed
MCOR = -ve no printing
MCOR = +ve correlations above MCOR printed

CONV convergence criterion; LSQ cycling is terminated if the

maximum shift/esd < CONV (default 0.01)

The data files whose names were given on the L DATA cards . They should be lists of hkl and observations of the type and in the format indicated by the associated REFI and MODE.

Output:

The usual listing file reporting the data which have been read. This file also contains the output listings requested by the I PRIN card as well as the R-factors and chisqrd at the end of each least squares cycle.
A new crystal data file corresponding to the structure at the end of the least squares refinement.

Running the program:

On running the program the user is asked for the name of the crystal data file.
The value of \$\chi^2\$ for each data set is reported on the terminal at the end of each cycle.
Just before the last cycle user is asked for a name for the new crystal data file.

Calls:

APSHSF CALCFR CALCPA CALMMG CENTRE DFLTMG ERRMES FINDCD GMEQ GMUNI INDFIX LFCALC LMCALC LOGMAG LSETSF MATCOR MATINV MATSET MATSHF MATTOT MGTDOM NWINSF PARRUN PARSSF PREFIN PRIDOM PRNCYC RELATE RFACS SETABS SETFCM STLSSF VARMAK VARSSF WGHTSF

Common blocks used:

/DERBAS/ to use LVARB

/CARDRC/ to use ICDN

/DSOURC/ to use NUMSRC JSRC MSRC NOBSRC SRCPAR

/EXTN/ to use IEXTYP CEXT PATHS

/FCAL/ to use FCMOD

/IOUNIT/ to use LPT ITO

/MCAL/ to use FMCMOD

/NEWOLD/ to use AMAXSH

/OBSCAL/ to use OBS GCALC YCALC DIFF ICODE SUMWD WT WDIFF

/POLDA/ to use POLUP POLDW POLND

/POSNS/ to use NATOM

/PRBLEM/ to use NFAM LF1SP LF3SP

/REFINE/ to use IREF NCYC NCYC1 LASTCY ICYC MAG CONV

/SFDATA/ to use all members

/SATELL/ to use IPROP KCENT

/SCLDAT/ to use ISCALE SCALE

/SYMMAG/ to use MTYP NDOM FERA HELI

/TWIN/ to use TWMAT NTWIN MTWIN

/WDSPC/ to use IWDNUM

*** SNPLSQ multiple source magnetic LSQ including SNP C4.7 PJB March 2008 ***

Specific Least Squares Refinement . . . . . . . Setting Up

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P. Jane Brown

Institut Laue Langevin,
Grenoble, FRANCE