:orphan: .. index:: *QUADRATIC RESPONSE .. _*QUADRATIC RESPONSE: ==================== \*QUADRATIC RESPONSE ==================== This section gives directives for the calculation of quadratic response functions :cite:Saue2002a. General control statements ========================== .. index:: .PRINT .. _QUADRATIC_RESPONSE_.PRINT: .PRINT ------ Print level. *Default:* :: .PRINT 0 Definition of the quadratic response function ============================================= .. index:: .DIPLEN .. _QUADRATIC_RESPONSE_.DIPLEN: .DIPLEN ------- Specification of dipole operators for A, B, and C (see :ref:one_electron_operators for details). .. index:: .A OPERATOR .. _QUADRATIC_RESPONSE_.A OPERATOR: .A OPERATOR ----------- Specification of the A operator (see :ref:one_electron_operators for details). .. index:: .B OPERATOR .. _QUADRATIC_RESPONSE_.B OPERATOR: .B OPERATOR ----------- Specification of the B operator (see :ref:one_electron_operators for details). .. index:: .C OPERATOR .. _QUADRATIC_RESPONSE_.C OPERATOR: .C OPERATOR ----------- Specification of the C operator (see :ref:one_electron_operators for details). .. index:: .B FREQ .. _QUADRATIC_RESPONSE_.B FREQ: .B FREQ ------- Specify frequencies of operator B. *Example:* 3 different frequencies. :: .B FREQ 3 0.001 0.002 0.01 *Default:* Static case. :: .B FREQ 1 0.0 .. index:: .C FREQ .. _QUADRATIC_RESPONSE_.C FREQ: .C FREQ ------- Specify frequencies of operator C (see :ref:QUADRATIC_RESPONSE_.B FREQ). .. index:: .ALLCMB .. _QUADRATIC_RESPONSE_.ALLCMB: .ALLCMB ------- Evaluate all nonzero quadratic response functions and thereby disregarding analysis of overall permutational symmetry. *Default:* Evaluate only unique, nonzero, response functions. Excited state properties ======================== **This page describes unreleased functionality. The keywords may not be available in your version of DIRAC.** First order properties of excited states can be computed from the quadratic response function. .. index:: .EXCPRP .. _QUADRATIC_RESPONSE_.EXCPRP: .EXCPRP ------- Give the number of "left" and "right" states in each boson symmetry. *Example*: :: .EXCPRP 5 5 5 5 0 0 0 0 Compute the excited state expectation values \|\\langle i\|\\hat{A}\|i\\rangle|, where i goes from 1 to 5 in each symmetry (four symmetries in this case). The zeros can be substituted with positive integers to generate transition state moments \|\\langle i\|\\hat{A}\|j\\rangle|. Control variational parameters ============================== .. index:: .SKIPEE .. _QUADRATIC_RESPONSE_.SKIPEE: .SKIPEE ------- Exclude all rotations between occupied positive-energy and virtual positive-energy orbitals. .. index:: .SKIPEP .. _QUADRATIC_RESPONSE_.SKIPEP: .SKIPEP ------- Exclude all rotations between occupied positive-energy and virtual negative-energy orbitals. Control reduced equations ========================= .. index:: .MAXITR .. _QUADRATIC_RESPONSE_.MAXITR: .MAXITR ------- Maximum number of iterations. *Default:* :: .MAXITR 30 .. index:: .MAXRED .. _QUADRATIC_RESPONSE_.MAXRED: .MAXRED ------- Maximum dimension of matrix in reduced system. *Default:* :: .MAXRED 100 .. index:: .THRESH .. _QUADRATIC_RESPONSE_.THRESH: .THRESH ------- Threshold for convergence of reduced system. *Default:* :: .THRESH 1.0D-5 Control integral contributions ============================== The user is encouraged to experiment with these options since they may have an important effect on run time. .. index:: .INTFLG .. _QUADRATIC_RESPONSE_.INTFLG: .INTFLG ------- Specify what two-electron integrals to include (default: :ref:HAMILTONIAN_.INTFLG under :ref:**HAMILTONIAN). .. index:: .CNVINT .. _QUADRATIC_RESPONSE_.CNVINT: .CNVINT ------- Set threshold for convergence before adding SL and SS integrals to SCF-iterations. *2 (real) Arguments:* :: .CNVINT CNVXQR(1) CNVXQR(2) *Default:* Very large numbers. .. index:: .ITRINT .. _QUADRATIC_RESPONSE_.ITRINT: .ITRINT ------- Set the number of iterations before adding SL and SS integrals to SCF-iterations. *Default:* :: .ITRINT 1 1 Control trial vectors ===================== .. index:: .XQRNRM .. _QUADRATIC_RESPONSE_.XQRNRM: .XQRNRM ------- Normalize trial vectors. Using normalized trial vectors will reduce efficiency of screening. *Default:* Use un-normalized vectors. Advanced/debug flags ==================== .. index:: .NOPREC .. _QUADRATIC_RESPONSE_.NOPREC: .NOPREC ------- No preconditioning of initial trial vectors. *Default:* Preconditioning of trial vectors. .. index:: .RESFAC .. _QUADRATIC_RESPONSE_.RESFAC: .RESFAC ------- New trial vector will be generated only for variational parameter classes whose residual has a norm that is larger than a fraction 1/RESFAC of the maximum norm. *Default:* :: .RESFAC 1000.0