NEGATIVE QUARTET ESTIMATES BY EMBEDDING OF TRIPLET AND QUINTET INVARIANTS

被引:4
作者
ALTOMARE, A [1 ]
BURLA, MC [1 ]
CASCARANO, G [1 ]
GIACOVAZZO, C [1 ]
GUAGLIARDI, A [1 ]
MOLITERNI, AGG [1 ]
POLIDORI, G [1 ]
机构
[1] UNIV PERUGIA,DIPARTIMENTO SCI TERRA,I-06100 PERUGIA,ITALY
来源
ACTA CRYSTALLOGRAPHICA SECTION A | 1995年 / 51卷
关键词
D O I
10.1107/S0108767394012754
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Negative quartet invariants play an important role in direct procedures: they can be actively used in the phasing process or, in a passive way, for selecting the correct solution in multisolution approaches. Unfortunately their average reliability is small. The use of the second representation of the quartets may lead to improved estimates but calculations are expected to be too extensive even for modem computers. The simple and fast process described in this paper provides improved quartet estimates by embedding triplet and quintet estimates. The first applications of the method are satisfactory.
引用
收藏
页码:305 / 309
页数:5
相关论文
共 26 条
  • [1] SIR92 - a program for automatic solution of crystal structures by direct methods
    ALTOMARE, A
    CASCARANO, G
    GIACOVAZZO, G
    GUAGLIARDI, A
    BURLA, MC
    POLIDORI, G
    CAMALLI, M
    [J]. JOURNAL OF APPLIED CRYSTALLOGRAPHY, 1994, 27 : 435 - 435
  • [2] ON THE RELIABILITY OF QUARTET ESTIMATES
    ALTOMARE, A
    BURLA, MC
    CASCARANO, G
    GIACOVAZZO, C
    GUAGLIARDI, A
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1993, 49 : 342 - 346
  • [3] THE JOINT PROBABILITY-DISTRIBUTION OF ANY SET OF PHASES GIVEN ANY SET OF DIFFRACTION MAGNITUDES .2. PRACTICAL APPLICATIONS
    BURLA, MC
    CASCARANO, G
    GIACOVAZZO, C
    [J]. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, 1992, 48 : 906 - 912
  • [4] USE OF QUINTETS IN DIRECT PROCEDURES - SOME PRACTICAL ASPECTS
    BURLA, MC
    POLIDORI, G
    NUNZI, A
    CASCARANO, G
    GIACOVAZZO, C
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1977, 33 (NOV): : 949 - 953
  • [5] STRENGTHENING OF QUARTET INVARIANT ESTIMATES VIA THE PRIOR ESTIMATION OF TRIPLET RELATIONSHIPS
    BURLA, MC
    CASCARANO, G
    GIACOVAZZO, C
    GUAGLIARDI, A
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1994, 50 : 325 - 329
  • [6] THE METHOD OF REPRESENTATIONS OF STRUCTURE SEMINVARIANTS - THE STRENGTHENING OF TRIPLET RELATIONSHIPS
    CASCARANO, G
    GIACOVAZZO, C
    CAMALLI, M
    SPAGNA, R
    BURLA, MC
    NUNZI, A
    POLIDORI, G
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1984, 40 (MAY): : 278 - 283
  • [7] THE JOINT PROBABILITY-DISTRIBUTION OF ANY SET OF PHASES GIVEN ANY SET OF DIFFRACTION MAGNITUDES .3. A FUNCTION TO MAXIMIZE
    CASCARANO, G
    GIACOVAZZO, C
    MOLITERNI, AGG
    POLIDORI, G
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1994, 50 : 22 - 27
  • [8] CASCARANO G, 1995, UNPUB ACTA CRYST
  • [9] RELATIONS BETWEEN THE PHASES OF STRUCTURE FACTORS
    COCHRAN, W
    [J]. ACTA CRYSTALLOGRAPHICA, 1955, 8 (08): : 473 - 478
  • [10] THE USE OF A HIGH-SPEED DIGITAL COMPUTER FOR THE DIRECT DETERMINATION OF CRYSTAL STRUCTURES .2.
    COCHRAN, W
    [J]. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES, 1957, 243 (1233): : 281 - 288