COPL: program for obtaining a complete list of order parameters for a group- subgroup crystalline phase transition
COPL: program for obtaining a complete list of order parameters for a group- subgroup crystalline phase transition
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COPL：用于获取族-子族结晶相变的有序参数的完整列表的程序
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
D. M. Hatch
中科院分区：
文献类型：
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作者：
H. Stokes;D. M. Hatch
在晶体相变中，高对称性相和低对称性相的空间群对称性通常表现为群±子群关系：L H.在朗道相变理论中，这种相变是用序参数(OPs)来描述的。每个这样的OP都是由H的不可约表示(IR)表示的De®Ned空间中的n维向量g。IR将每个算子h2H映射到n n矩阵D(H)上。对于给定的算符g，满足dhg=g的算符h2H组成一个群L0使得L L0H。主要算符是那些L0=L的算符，它们决定低对称相的对称性。其他行动是次要行动。(在耦合操作的情况下，这种情况可能会变得更加复杂。)该程序的目的是生成与给定的空间群±子群对L H相关联的主要和次要操作的完整列表。该列表的生成是对广义朗道逆问题的解(Ascher&Kobayashi，1977；Ascher，1977)。
In a crystalline phase transition, the space-group symmetries of the highand low-symmetry phases often exhibit a group±subgroup relation: L H. In the Landau theory of phase transitions, this transition is described by order parameters (OPs). Each such OP is an n-dimensional vector g in the space de®ned by an irreducible representation (IR) of H. The IR maps each operator h 2 H onto an n n matrix D(h). For a given OP g, the operators h 2 H which satisfy Dhg = g form a group L0 such that L L0 H. The primary OPs are those for which L0 = L. They determine the symmetry of the low-symmetry phase. The other OPs are secondary OPs. (This situation can become more complex in the case of coupled OPs.) The aim of the program is to generate a complete list of OPs, both primary and secondary, associated with a given group±subgroup pair of space groups L H. The generation of this list is a solution to a generalization of the inverse Landau problem (Ascher & Kobayashi, 1977; Ascher, 1977).