Exact property estimation from diffusion Monte Carlo with minimal stochastic reconfiguration /

Our objective is to develop a diffusion Monte Carlo (DMC) algorithm to estimate the exact expectation values, ($o|^|^o), of multiplicative operators, such as polarizabilities and high-order hyperpolarizabilities, for isolated atoms and molecules. The existing forward-walking pure diffusion Monte Carlo (FW-PDMC) algorithm which attempts this has a serious bias. On the other hand, the DMC algorithm with minimal stochastic reconfiguration provides unbiased estimates of the energies, but the expectation values ($o|^|^) are contaminated by ^, an user specified, approximate wave function, when A does not commute with the Hamiltonian. We modified the latter algorithm to obtain the exact expectation values for these operators, while at the same time eliminating the bias. To compare the efficiency of FW-PDMC and the modified DMC algorithms we calculated simple properties of the H atom, such as various functions of coordinates and polarizabilities. Using three non-exact wave functions, one of moderate quality and the others very crude, in each case the results are within statistical error of the exact values.

Exploring the Family Context Among Children Adopted From China: Perceptions of Pre-Adoption Factors, Post-Adoption Experiences, and the Quality of Parent-Child Relationships

Within the context of international adoption, previous research has focused on parentchild attachment relationships and various aspects of the adoption process. However, less is known about other aspects of parent-child relationships (e.g., cohesion, conflict) within internationally adoptive families. Additionally, there is a need for research that explores both parent and child perceptions of the process of adoption - including pre- and post-adoptive factors - and its connection to the quality of parent-child relationships. This research utilized a qualitatively-oriented methodology to conduct separate, in-depth interviews with 10 adoptive Canadian mothers and their adopted Chinese children (aged 9 to 11 years). Results highlight parent and child reports of mainly strong, positive relationships. Several pre-adoption experiences are examined, including institutionalization, age at the time of adoption, and parental stress/expectations. A key finding concerns the link that adoptive parents perceive between the quality of their child's pre-adoptive care (i.e., mainly early institutionalized care) and the quality of their relationship. Interestingly, this link is perceived in two different ways - either as a challenge for the parent-child relationship or as a means to strengthen it. Post-adoption experiences are also explored, including cultural socialization, creating a transracial family, discussing adoption, parental stress, and sibling involvement. A key finding involves parent and child reports that cultural socialization efforts (i.e., familiarizing children with Chinese culture) are linked to more positive parent-child relationships. The implications of these findings are discussed in relation to theory and practice within the context of international adoption.